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Wick System
3Mar

Hydroponic System: Wick System

By | March 3, 2017

Wick System

 

The wick system is the simplest of all six types of hydroponic systems. That’s because traditionally it doesn’t have any moving parts, thus it doesn’t use any pumps or electricity. However some people still like using an optional air pump in the reservoir. Because it doesn’t need electricity to work, it’s also quite useful in places where electricity cant be uses, or is unreliable.

The wick system is an easy type of system to build when first learning about hydroponics, and/or you just your want to get your feet wet first. This type of hydroponic system is also often used by teachers in classrooms as experiments for kids. Both to help explain how plants grow, as well as getting them interested in hydroponics.

What you need to build a wick system:
  • A bucket or container for the plant.
  • A bucket or container for the reservoir.
  • A good wicking growing media like coco coir, Vermiculite, or perlite.
  • Some strips of material like felt or good wicking rope.

How a wick system operates is like it sounds, it basically just wicks up nutrient solution from the reservoir to the plants using the process of capillary action. Meaning it sucks up water to the plants through the wick like a sponge. Typically good wick systems will have at least two or more good size wicks to supply enough water (nutrient solution) to the plant. The bucket/container with the plant in it basically sits right above the container used for the reservoir. That way the water doesn’t need to travel up very far to get to the growing media with plants.

Downside of wick systems
The biggest downside’s to a hydroponic wick systems is that they don’t really work well for larger plants that need to drink up more water. Their really more suited to grow smaller non-fruiting plants, like lettuce and herbs. While the wick does suck up (wick up) moisture to the plants roots, the larger the plant is, the more water it will need to drink up. If they are fruiting plants, they will need even more water to support the growth of all the water absorbing fruit as well.

Wick systems also have the disadvantage of being less efficient at delivering nutrients. Heavier feeding plants may need nutrients faster than the wicks can supply them to the roots. Lettuce and herbs are generally light feeders, while plants like tomato’s, peppers and most fruiting plants are heavier feeders.

Another downside to wick systems is that plants don’t absorb nutrients and water evenly, and the wick cant tell what nutrients the plant needs. The plants take the nutrients and water it needs, and leaves the rest of the nutrients in the growing medium. This can eventually cause a toxic buildup of mineral salts in the growing media. So flushing the excess nutrients from the root zone (growing media) with plain fresh water should be done regularly, like once a week or so.

Wicks
The wick itself is probably the most important part of the wick system, because without a good absorbent wick the plants would not get the moisture and nutrients it needs. You will likely need to do some testing of different materials to see what works best for you. When looking for a good wicking material, you’ll want to use something that’s absorbent, but is still resistant to rotting. Then washing the wick good first before you use it, can significantly improve the wicking ability of most materials.

Some common materials people have used for wick systems are things like, fibrous rope, propylene felt strips, tiki torch wicks, rayon rope or mop head strands, braided polyurethane yarn, wool felt, wool rope or strips, nylon rope, cotton rope, stripe of fabric from old clothing or blankets etc. etc.

Make sure to use enough wicks to support the plants water usage. That will depend greatly on how you build your wick system, type of plant your growing, and growing medium you use. You’ll likely need at least 2-4 wicks unless it’s a real small system. Also the shorter up the wick the water has to go from the reservoir to the growing media and roots, the more water it can transport to the growing media.

Once the nutrient solution makes it up the wick to the growing media, you want to use a very absorbent growing media to further wick up and hold moisture. Some of the most commonly used growing media’s for wick systems are things like coco coir, Vermiculite or perlite. And in some cases, even water absorbing polymer crystals have been used too.

The Reservoir
The wick system reservoir can be large or small, you just don’t want it to ever run dry. Also you want the water level to remain high enough so the water (nutrient solution) doesn’t need to travel up very far to get to the growing media and root zone. You’ll want to top off the reservoir with fresh nutrient solution as needed, as well as clean it out and change it completely once in a while too. Simply because algae and/or microorganisms can begin growing in the food rich water, especially if it’s not light proof.

Because the wick sucks up water and nutrients evenly, and the plants don’t use or absorb them evenly, a build up of excess nutrient salts can build up in the growing media over time. So you’ll want to flush it with plain fresh water regularly as well. Probably something like about every couple weeks. That will reduce the likelihood of the nutrient salts building up and reaching toxic levels for the plants.

Optional air pump
Using an air pump and air stone to aerate the water in a wick system isn’t necessary, however it can be beneficial. While the roots should be able to get oxygen from the small air pockets in the growing medium, they also absorb dissolved oxygen directly from the water itself as well. Along with helping to aerate the water, the moving, and rising bubbles keep the water circulating. Keeping the nutrient solution water moving around keeps the nutrients in it evenly mixed up all the time. If the water is still, the nutrients can settle toward the bottom over time. However if you are going to use an air pump anyway, you may want to just build a water culture system instead.

 

Aeroponic System
3Mar

Hydroponic System: Aeroponic System

By | March 3, 2017

Aeroponic System

 

While the concept of the aeroponic system is quite simple, it’s actually the most technical of all 6 types of hydroponic systems. However it’s still fairly easy to build your own basic aeroponic system, and a lot of home growers like growing in them as well, and even get really good results using this type of hydroponic system.

Like with any other type of hydroponic system, you can use many different kinds of materials to build it, as well as many different types of design setups to fit in your space. Your really only limited by the space you have, and your imagination.

Some advantages to using an aeroponic systems are they typically use little to no growing media. The roots get maximum oxygen, and the plants grow more rapidly as a result. Aeroponic systems also generally use less water than any other type of hydroponic system (especially true aeroponic systems). Also harvesting is usually easier, especially for root crops.

However there are a few downsides to aeroponic systems as well. Besides being a bit more expensive to build. The mister/sprinkler heads can clog from build up of the dissolved mineral elements in the nutrient solution. So make sure to have extras on hand to swap out when they do clog while you clean them. Also because the plants roots are hanging in mid air by design in aeroponic systems, the plants roots are much more vulnerable to drying out if there is any interruption in the watering cycle. Therefor, even any temporary power outage (for any reason) could cause your plants to die much more quickly than any other type of hydroponic system. Also there’s a reduced margin for error with the nutrient levels in aeroponic systems, especially the true high pressure systems.

What you’ll need to build your own basic Aeroponic system:
  •  Container to hold the nutrient solution (a reservoir).
  • Submersible fountain/pond pump.
  • Tubing to distribute water from the reservoir pump to the mister heads in the growing chamber.
  • Enclosed growing chamber for the root zone.
  • Mister/sprinkler heads.
  • Water tight container for the growing chamber where the plants root systems will be.
  • Tubing to return the excess nutrient solution back to the reservoir.
  • Timer (preferably a cycle timer) to turn on and off the pump.

How the aeroponic system operates is a fairly easy concept. First the purpose of the roots hang in mid air is so they can get the maximum amount of oxygen that they can get. The high volume of oxygen the roots get allows the plans to grow faster than they would otherwise, and the main benefit to this type of hydroponic system.

Second, there is typically very little if any growing media is used, exposing all the plants roots. The plants are suspended either by small baskets, or closed cell foam plugs that compress around the plants stem. These baskets or foam plugs fit in small holes at the top of the growing chamber. The roots hang down inside the growing chamber where they get sprayed with nutrient solution from mister heads at regular short cycles. The regular watering cycles keep the roots moist and from drying out, as well as provides the nutrients the plants need to grow.

The growing chamber the roots are in should be light proof, and almost air tight. It does need to allow fresh air in so the roots can get plenty of oxygen, but you don’t want water to spill out, or pests to get in. Also you want the root chamber to hold in humidity. Ultimately what you want is the roots to get plenty of moisture, fresh oxygen, and nutrients. A a well designed aeroponics system provides a good balance of all three of those elements to the roots at the same time.

Lastly, a major factor in aeroponic systems is the water droplet size. Roots sprayed with a fine mist will grow much faster, bushier, and with more surface area to absorb nutrients and oxygen with than roots sprayed with small streams of water like from small sprinkler heads. That translates into the plant canopy growing more rapidly as well. Aeroponic system types are categorized by the water droplet size.

There are three types of Aeroponic Systems

Low pressure Aeroponic Systems (soakaponics)
Also termed “soakaponics” low pressure aeroponic systems are what most people are familiar with when they think of aeroponics. That’s mainly because most all aeroponic systems sold at stores selling hydroponics supply’s are low pressure systems. While the low pressure systems work very nicely, the large water droplet size is much different than in the high pressure systems.

The main reason the low pressure aeroponic systems are so popular is that they don’t require much more in the way of cost or special equipment than other types of hydroponic systems. The simplicity and low cost of low pressure systems makes this type of aeroponic system very attractive to many home growers.

While you don’t need any special equipment or a special water pump. The standard fountain/pond pumps will do just fine. You do however want a pump that’s stronger than you would for any other type of hydroponic system. That’s the main and most important difference. That’s because the pressure in the system will drop some with each sprinkler head you add. Fountain and pond pumps don’t give a psi (pressure) rating, but the more GPH (gallons per hour) it can put out closer to the “max head height” the stronger (more pressure) the pump has.

You will want enough sprinkler heads that the spray overlaps, and completely covers the entire root zone. Even as the plants get bigger and the root mass gets bigger. As the root mass gets big, it’s often hard for the spray from the sprinkler heads to penetrate the thick root mass. If you design your low pressure aeroponic system so the roots are sprayed from above the root mass or near the top of it, the water will trickle down through the root mass much better than trying to spray them from below.

High pressure Aeroponic Systems (true aeroponic systems)
While the low pressure systems are the most common, high pressure aeroponic systems are the “true aeroponic” systems. That’s because it takes the higher pressure (60-90 psi) to properly atomize the water into a fine mist with a very small water droplet size. This fine mist allows the roots to get a lot more oxygen than in low pressure systems. However it’s more complicated and expensive to build a high pressure aeroponic system.

What you’ll need to build your own true high pressure Aeroponic system:
  • Accumulator tank (to act as the pressurized reservoir tank).
  • Solenoid valve (to open and close the feed line to the mister heads).
  • Cycle timer (to open and close the solenoid valve).
  • Fine spray mister heads (to spray the roots with a fine mist).
  • Small air compressor (to pressurize the accumulator tank).
  • Enclosed growing chamber for the root zone.
  •  A collection reservoir to collect the runoff if you plan to recirculate the nutrient solution.

While the basic design of the growing chamber and plant support can remain the same as with low pressure systems. The water (nutrient solution) delivery system is much different. Because of how often a pump would need to turn on and off  (100’s to 1,000’s of times a day) it would ware out very quickly. So the water pump is eliminated in high pressure aeroponic systems.

To do that they pressurize the reservoir. The easiest way to do that is by using an accumulator tank similar to the type used in RO (reverse osmosis) water systems. It’s basically nothing more than a tank with a rubber divider/diaphragm in the center, creating two sides. Water (nutrient solutions) goes in one side, and compressed air goes in the other. The air is filled until the pressure reaches about 60 to 90 psi. That pressure pushes against the rubber diaphragm and pressurizes the reservoir side with the nutrient solution in it to the same psi.

A water line runs from the reservoir to the mister heads in the enclosed growing chamber to mist the roots. A Solenoid valve is used to open and close the water flow through the line to the mister heads. The Solenoid valve open and close timing is controlled by a cycle timer. The cycle timer can open and close the Solenoid for as little as one second, to as long as the grower wants. Typically it’s open/on for just a few seconds at a time, and off for only minutes before it sprays again. The cycle timer opens and closes the solenoid watering the plants roots with mist on this type of “on/off cycle” all day long.

Ultrasonic fogger
Ultrasonic fogger have also been used to create a mist in aeroponic systems, however with mixed results. Ultrasonic fogger are most commonly used to create visual displays in ponds, as well as on stage. They are also often sold around Halloween with the Halloween decorations too. While they do create a mist with a very small water droplet size, there is very little actual moisture in the mist/fog.

The mist created from ultrasonic foggers also tends to drop to the bottom of the container. Making it hard to make sure the roots are completely covered by the mist all the time. Another issue with using fogger is that the plates tend to clog with mineral build up. The only plates that have shown to work with any reliability are the more expensive Teflon heads. They can sometimes be cleaned using white vinegar, or water and pH down, and wiping them off with a Q-tip. Some growers have combined using ultrasonic foggers along with the low pressure aeroponic design in the same system.

 

 

Water Culture System
3Mar

Hydroponic System: Water Culture System

By | March 3, 2017

Water Culture System

 

Water Culture systems are about the simplest of all six types of hydroponic systems. While technically simple, they are still very effective for growing plants hydroponiclly. Not only do a lot of home hydroponic growers really like using water culture systems, but many commercial growers use this type of system on a large scale as well. Mainly because the water culture systems is a simple and easy concept. It’s also a very inexpensive type of system to build, and another reason why it’s popular with home growers as well. Even though the concept is simple, there are plenty of imaginative ways to use and build water culture systems out of different materials.

What you need to build a Water Culture system:
  • Container to hold the nutrient solution (reservoir)
  • Aquarium air pump
  • Air line/hose
  • Air stones (or soaker hose) to create the small bubbles
  • Baskets, pots, or cups to hold the plants
  • Some type of growing media

How a hydroponic Water Culture system operates is easy. The plant is actually suspended in baskets right above the nutrient solution in the reservoir. Usually by styrofoam floating on top, or through holes cut in the lid covering the reservoir. The roots hang down from baskets the plants are in, and hang down directly into the nutrient solution where they are submerged. The roots remain submerged all the time 24/7. The roots don’t suffocate because they get the air and oxygen they need from  air bubbles rising through the nutrient solution, as well as from dissolved oxygen in the water itself.

The more air bubbles the better for water culture systems. The bubbles rising should make the water look like water boiling at a heavy rolling boil. The bubbles should be rising up through, and making direct contact with the roots as they rise to the top of the water to be most effective for the plants. There are actually two ways of providing aeration and dissolved oxygen to the nutrient solution.

Types of aeration

 

Air bubbles
An aquarium air pump and air stones are typically used to provide air bubbles to the nutrient solution for water culture systems, as well as other types of hydroponic systems. The air pump provides the air volume, and is connected to air stones with an air line/tubing. The air stones are made of a porous rock like material, the small pores create small individual air bubbles that rise to the top of the water (nutrient solution).

Soaker hose can be used in place of air stones to create the air bubbles as well. The soaker hose creates even smaller air bubbles. The smaller the air bubbles, the better for aerating the nutrient solutions. Smaller air bubbles provide more contact surface with the water. The contact between the air bubbles and water helps to replace the dissolved oxygen taken up by the plants roots.

Falling water
Though not typical in water culture systems for home growers, surface agitation from falling water splashing around is another very good way of aerating the nutrient solution. The higher the water is falling from, and/or the more volume of water falling, the more downward force it has when it hits the waters surface. The more downward force, the deeper the agitation and more aeration (dissolved oxygen) provided. This method of aeration is more common in commercial water culture systems because they use large volumes of water compared to home growers.

Recirculating Water Culture systems
Another variation of the typical water culture system is a recirculating water culture system. The recirculating system works like a flood and drain system but never drains. You can have as many growing containers (water culture reservoirs) as you want connected to one central reservoir. Each growing container has its own fill line, as well as a drain/overflow tube that drains back to the central reservoir.

Some growers will use buckets instead of wide shallow containers. Each bucket with their own plant in it, and of coarse filled with nutrient solution. They may have a row of these buckets. Using a fountain/pond pump to pump the nutrient solution up to each of the buckets. As the water fills the buckets, the excess water spills over into the overflow tube and flows back to the reservoir where it’s recirculated back through the system again.

Most growers that recirculate the nutrient solution like this for their water culture systems only use an air pump in the central reservoir, rather than in each individual bucket (mainly to save money). They let the water pump run 24/7 all the time. However if you have air bubbles running in each bucket like a typical water culture system, you can vary the on time for the water pump. Also the plants would benefit from the direct contact with the rising air bubbles contacting the roots.

Recirculating the water allows you to be able to utilize falling water as a source of aeration in the system. Also you don’t need to keep checking the water level in each container to replace the water the plants drank up (you just check and replace it in the central reservoir), a nice benefit when you are growing large, or many plants in the same system. Just about all the large commercially operated water culture systems recirculate water through the system.

DWC (Deep Water Culture) 

The term “DWC” is often used incorrectly when describing water culture systems. So what is “DWC,” and why isn’t “DWC” one of the six types of hydroponic systems? Well, that’s because it’s simply not a different type of hydroponic system at all. As you can see by the full name “Deep Water Culture,” it’s just a variation of the already existing type of hydroponic system called a water culture system. The word “Deep” in front is only used to describe some water culture systems when the water depth in the system is deeper than 8-10 inches, then it can be defined as an actual DWC system. However regardless of the water depth, DWC systems are still water culture systems.

Most of the time the water/nutrient solution depth doesn’t need to be deeper than 8 inches. That’s really only needed for larger plants that have larger root systems that need more space, and/or drink up a lot more water. Or when using a container like a bucket that needs to be filled high enough to reach the plants main root ball near the top sufficiently. Plants like the size of most varieties of lettuce can easily be grown using only 4-6 inches of water in water culture systems.

Now with that said, their’s no difference between how a typical water culture system and a DWC (deep water culture) system works or  functions. Their exactly the same, the only difference between the two is the depth of the water in the system. Regardless of whether it’s a typical water culture system, an actual DWC system, or even a recirculating standard water culture or true DWC system, you still want to make sure you have enough water volume, and good oxygenation to the root system to support the plants. Even when they reach full size.

Water volume is different than water height. If you take a gallon of water and pour it in a wide bucket, the water height may only be a inch or two high, but you pour the same gallon of water in a 3 inch wide tube, the water height will be closer to 2 feet high. So water volume and height are two completely different things.

Should the water level be above or below the baskets?

There’s often confusion and sometimes maybe even debate on where the water/nutrient solution level should be in water culture systems. Should the basket be touching the water, or hanging just above it? There are pros and cons for both, but there is no right or wrong, it can be either. The water level is also very quick and easy to change in a water culture system by simply adding more water, or taking some out.

When the air bubbles reach the top of the water, they pop on the waters surface. When they pop they splash tiny little water droplets  an inch or two above the water’s surface. How much of these tiny water droplets get splashed around depends largely on how much air is actually being supplied, and thus how many air bubbles are rising to the surface from the air stones.

When the basket is not touching the water and hanging just above it, these tiny splashing water droplets help keep the growing media near the bottom of the baskets damp. How damp depends on how many air bubbles there are popping and splashing on the water’s surface near the basket. A good comparison is comparing it to boiling water (heavy rolling boil, a rolling boil, boiling, just simmering). With a heavy rolling boil being best, and just simmering being minimal. Another factor is the type of growing media that’s being used. Some growing media will absorb and hold moisture quicker and easier than others, and that will make a big difference as well.

When the basket’s are touching the water, the growing media in the baskets can absorb/wick up more water than if they were hanging above it, and this can sometimes be beneficial. But here again the type of growing media is going to make a big difference because some growing media will absorb and hold moisture quicker and easier than others. Thus can become completely water logged near the bottom of the baskets if it’s in constant contact with the water. If it does, just lower the water level so the baskets are hanging above the water instead, or use a different type of growing media.

It’s also important to mention that how big the plant is makes a difference as well. The plants roots will fallow the water/nutrient solution. Meaning they will go, and grow anywhere that has moisture. If the plant is small and the roots haven’t grown out the bottom of the basket yet, it may be beneficial to have the baskets touching the water. At least until the roots are growing out the bottom and long enough to remain submerged.

Even when the bottom of the baskets are nice and moist from plenty of tiny water droplets splashing around by the popping air bubbles while hanging above the water. The extra moisture close to the plants main root ball from the growing media directly wicking up water/nutrient solution while the baskets are touching the water, can speed up root growth while the plants and root mass are still small.

The Kratky Method

To begin with I first need to say the called Kratky method is not a new or different type of hydroponic system. I say “so called” because it’s really just variation of a standard water culture system, but has sometimes been commonly referred to by a person’s name (renaming it) instead. As far as I can tell, the variation was dubbed the Kratky Method after B.A. Kratky at the University of Hawaii who teaches non-recirculating hydroponic methods.

Non recirculating hydroponic systems (also referred to as “run to waste” systems) don’t circulate water/nutrient solution from the reservoir to the plants and back again to the reservoir. They still pump water from the reservoir to the plants, but then allow the water/nutrient solution to drain off onto the ground, or into a drain system to discard any runoff. It sounds wasteful, but non recirculating systems can be very efficient and have very little runoff if done right. Water culture systems by definition are non-recirculating, but can be modified to be circulating systems as well.

The hydroponic system sometimes referred to as the Kratky method is simply a water culture system without the air pump, as well as part NFT system. It’s a water culture system because the plants hang above the water/nutrient reservoir the roots hang down into. It’s also part NFT system because like NFT systems, there is a gap between the basket holding the plant and water the roots sit in. This gap is an air pocket and is supposed to replace the air pump in a standard water culture system.

While the plants are small the basket is supposed to touch the water so the roots can begin growing out the bottom. As the plants grow and the roots get longer, the plant drinks up some of the water as well. That lowers the water level leaving a air gap. Without the air pump to replace the dissolved oxygen and oxygenate the water, the plant’s need the air gap to be able to get the oxygen from. This type of system design is useful in places where electricity is non existent or unreliable.

However this methods does have it’s distinct drawbacks. The air pump does more than just supply dissolved oxygen in water culture systems. The rising bubbles also keep the water moving around. When the water/nutrient solution is stagnant, the mineral salts (nutrients) settle near the bottom. As a result the nutrient balance becomes uneven (very strong near the bottom, and very weak near the top). The rising air bubbles from the air pump create movement in the water that keeps the nutrient solution mixing all the time, and thus nutrients evenly distributed throughout the water as well.

Also, while the plants roots are able to get oxygen when using the Kratky method, the roots above the water line cant get nutrients, and the roots below the water line cant get oxygen because they have already depleted the dissolved oxygen in the water early on, and there is nothing to replace it. That’s a source of stress for the plant. Think of it like being in swimming pool and not being able to move while having your nose above water so you could breath, and having your mouth below the water line and able to drink water so you don’t dehydrate. You can survive this way if you had to, but it would be very uncomfortable.

Plants are adaptable and will always try to adapt to their environment and surroundings as best they can. But the conditions provided when using the Kratky method are far from ideal conditions. While they are far from ideal conditions, and the cost to run an air pump 24/7 and/or otherwise replace the dissolved oxygen is extremely low. In areas where the electricity is very unreliable or nonexistent, the Kratky method can be a beneficial and useful option.

 

Nutrient File Technique
3Mar

Hydroponic System: NFT – Nutrient Film Technique System

By | March 3, 2017

N.F.T. (Nutrient Film Technique) System

 

The N.F.T. system  (Nutrient Film Technique) is quite popular with home hydroponic growers as well. Mainly because of it’s fairly simple design. However N.F.T. systems are best suited for, and most commonly used for growing smaller quick growing plants like different types of lettuce. Along with growing lettuce, some commercial growers also grow different types of herbs and baby greens using N.F.T. systems.

While there are a lot of different ways design an N.F.T. system, they all have the same characteristic of a very shallow nutrient solution cascading downward through the  tubing. Where the bare roots of the plants come in contact with the water, and can absorb the nutrients from it. The major downside to an N.F.T. systems is that the plants are very sensitive to interruptions in the flow of water from power outages (or whatever reason). The plants will begin to wilt very quickly any time the water stops flowing through the system.

 What you need to build a N.F.T. system:
  • Container to hold the nutrient solution (a reservoir)
  • Submersible fountain/pond pump
  • Tubing to distribute water from the pump to the N.F.T. growing tubes
  • Growing tubes for the plants to grow in (also called a gully/channel)
  • starter cubes, or small baskets and growing media to start seedlings in
  • Return system (tubing, channels) to guide the used nutrient solution back to the reservoir

How a hydroponic  N.F.T. system  operates is fairly simple. Nutrient solution is pumped up from the reservoir, usually to a manifold that connects the larger tubing to a number of smaller ones. Each one of these smaller tubes runs nutrient solution to one side of each one of the growing channels/gully’s with the plants in it. A thin layer (film) of the nutrient solution flows through each of the channel’s with the plants in it to the other side, passing by each plant and wetting the roots on the bottom of the channel as it does. The nutrient solution flows from one side to the other because the channel is sloped slightly so the water flows down hill.

The plants in the growing tubes (channel/gully) are typically suspended above the water by placing seedlings started in starter cubes or small one inch baskets of growing media into small holes in the top of the tube. The roots of the seedlings hang down to the bottom of the tube/channel where they get nutrients from the shallow film of nutrient solution flowing by. The excess nutrient solution flowing out of the low end of each of the channels drains into another channel or tube, and guided back to the reservoir where it is recirculated through the system again.

While the nutrient solution flowing through the channels is very shallow, the entire plants root mass remains moist from the roots being able to wick up moisture on the outside of the roots, as well as through humidity that’s kept within the tube/channel. The roots that are suspended between the base of the plant and the water level in the channel not only have moisture to access, but are also able to get plenty oxygen from the air surrounding them within the tube/channel as well.

Commercial growers typically use specially made channels/gully’s for N.F.T. systems that have flat bottoms with grooves running lengthwise along the channel. These grooves allow water to flow underneath the root mass and help keep it from pooling or damming up. Home growers often use vinyl rain gutter down spouts for their channels. These vinyl down spouts have similar grooves, but cost just a fraction of what the commercially made channels/gully’s cost. Home growers also often use round ADS (Advanced Drainage System) irrigation tubing for N.F.T. systems. The ADS tubing doesn’t have grooves, but with increasing the slope to compensate, the round tubing works well also.

N.F.T. system Flow rate, and channel slope
How deep should the water be, and how fast should the water be flowing are the two most common questions asked about this type of system. First the slope of the channel controls how fast the water goes through the tube/channel (not the water pump or).

The recommended slope for a N.F.T. system is typically a 1:30 to 1:40 ratio. That is for every 30 to 40 inches of horizontal length, one inch of drop (slope) is recommended. We recommend when designing your N.F.T. systems, you design it so you can adjust the slope while the plants are still growing. That’s because as the root systems get bigger, they may cause it to pool and dam up the water flow. If it’s adjustable you can tilt it more to compensate if needed.  Also when building your N.F.T. systems, try and keep the channels/gully’s as true as possible. If they sag in spots, water will pool up in those areas.

The recommended flow rate for a N.F.T. system is typically between 1/4 gallon to 1/2 gallon per minute (1 to 2 liter’s) for each grow tube (channel/gully). Or between 15 gallons to 30 gallons per hour (60 to 120 liter’s). While the plants are just seedlings the recommended flow rate can be cut in half, and then increased as the plants get bigger. Flow rates much higher or lower than these have sometimes been associated with nutrient deficiencies. Also nutrient deficiencies have sometimes been seen when growing tubes (channel/gully) are longer than 30 to 40 feet (10 to 15 meters). However it’s been shown that having a second nutrient feed line half way down the growing tube (channel/gully) eliminates that issue.

 

EBB and Flow System
3Mar

Hydroponic System: EBB & Flow

By | March 3, 2017

Ebb & Flow – (Flood and Drain) System

 

Flood and Drain (Ebb and Flow) systems are very popular with home hydroponic growers for many reasons. Besides how easy they are for anyone to build, you can use almost any materials you have laying around to build them with, so you don’t need to spend much money to grow plants  hydroponically. Also they can be built to fit in any available space you might have (both indoors or outdoors), and there is no limit to the different and imaginative ways to design them for that space. Along with being inexpensive and easy to build, plants grow very well in flood and drain systems. The flood and drain system works basically like it sounds, by simply flooding the plants root system with nutrient solution. Only periodically rather than continuously.

How a hydroponic flood and drain system operates quite simple. The main part of the flood and drain system holds the containers the plants are growing in. It can be just one plant, or many plants/containers in series. A timer turns on the pump, and water (nutrient solution) is pumped through tubing from the reservoir up into the main part of the system using a submersible fountain/pond pump. The nutrient solution continues to fill (flood) the system until it reaches the height of the preset overflow tube so that it soaks the plants roots. The overflow tube should be set to about 2 inches below the top of the growing media.

When the water filling/flooding the system reaches the overflow tube height, it drains back down to the reservoir where it recirculates back through the system again. The overflow tube sets the water level height in the flood and drain system, as well as makes sure the water (nutrient solution) doesn’t spill out the top of the system while the pump is on. When the pump shuts off, the water siphons back down into the reservoir through the pump (draining the system).

What you need to build a Flood and Drain (Ebb and Flow) system:
  • A container for the plant’s roots to grow in.
  • A container (reservoir) to hold the nutrient solution.
  • A submersible fountain/pond pump.
  • A light timer to turn the pump on and off.
  • Some tubing to run from the pump in the reservoir to the system to be flooded.
  • An overflow tube set to the height you want the water level.
  • Growing medium of some kind.

There are many different ways to build a flood and drain system, and they are very good for growing small to medium size plants. Even for growing large plants with larger flood and drain system designs. You can use just about anything to build one including buckets, tubes, 2 liter bottles, storage totes, water bottles, an old ice chest, trash cans etc.. Just about anything that can hold water can be used. The imagination doesn’t stop there either, there are many ways to flood and drain the roots in the system too. Below are some examples of how the three most common ways used to flood and drain the systems work.

(Tip 1) Make sure there is a way air can get in the top of the overflow without spilling water out. A “T” connector with an extension that is a few inches above the water line will work nicely. This will keep air pockets from forming in the system and make sure it floods and drains properly.

(Tip 2) Make sure the overflow tube is bigger than the water inlet tube from the pump. Otherwise because the water is only going out through gravity, and water is coming in through pressure from the pump, you could wind up pumping in more water than what is going out the overflow. That would lead to water building up and spilling out the top of your system, unless you reduce the pressure (volume) from the pump.

There are basically three main types of flood and drain system setups

Plant containers in series design
This type of setup is most commonly used when many different containers with plants are being watered (flooded) at the same time. It’s important to remember that the system with the plants (containers) to be flooded (watered) needs to be above the reservoir, like on a table top or bench. That way the water can flow back to the reservoir by simple gravity, and thus drain the system correctly.

First multiple containers are all connected
together through tubing so that when the system is flooded, they all flood evenly, and all at the same time. For simplicity, instead of having a separate overflow for each container being flooded, there’s usually only one overflow tube. It connects to the system at the base where all the containers are connected to. And when the water height reaches the top of the overflow, it spills over and goes back to the reservoir to be pumped through the system again. The height of this one overflow tube will set the height of the water level in all of the connected containers with the plants in them (as long as it’s level). You can change the water height in all of the connected containers by simply adjusting the height of the single overflow tube.

Flooding tray design
The flooding table/tray flood and drain (ebb and flow) system type setup is useful when you want to place plants in the system temporarily, need to be moving them around a lot, or starting plants to be placed in another larger system. Instead of flooding separate containers with plants in it, this method only floods one container. Usually a shallow square or rectangle container that sets on top of a table. The reservoir usually sits directly underneath with easy access.

Water is pumped up from the reservoir into the flooding tray on one side, and the overflow is on the other side of the flooding tray. That makes sure the water actually circulates from one side of the tray/table to the other. Like any flood and drain (ebb and flow) system, the overflow tube height sets the water height during the flooding cycle, and can be adjusted as needed.

The plants are grown in regular plastic pots or baskets, and placed in the flooding tray like regular potted plants. However, unlike regular potted plants, hydroponic growing media is used to pot the plants instead of using potting soil. Once the plants get big enough, they can be transferred into a permanent hydroponic system.

One downside to using the flooding table is the algae growth, and should be cleaned out regularly. Because the top of the tray is usually left open, light is allowed to get in to the nutrient solution in the bottom of the tray, That allows algae to grow. The algae alone isn’t really bad for the plants, but it does use up dissolved oxygen in the water.

Serge tank flood and drain (ebb and flow) system design

The serge tank type of flood and drain setup is useful when more vertical space is needed. Typically with flood and drain systems, the reservoir is always lower than the hydropnic system. That’s so the water (nutrient solution) can drain out of the system through gravity back into the reservoir through the overflow, and when the pump is off. But you can still set up a flood and drain system even when the water level in the reservoir is higher than the hydroponic system it’s supposed to flood and drain back from. That is with the use of a serge tank.

The serge tank type of flood and drain system costs more to build because there are many more parts needed. It works on the principal that water seeks it’s own level. In other words, the water height in one container will be the same in another container when they are connected below the water line. The serge tank serves as a temporary reservoir that controls the water height in all the containers with the plants in them, and is only full during the flooding cycle.

The serge tank flood and drain (ebb and flow) system operates by pumping water (nutrient solution) from the much larger main reservoir into the serge tank when the pump timer goes on. As the water level rises in the serge tank, the water level rises evenly in all the connected plant containers at the same time. When the water level gets high enough, a float valve in the serge tank turns on a pump in the serge tank. The pump in the serge tank then pumps water back into the main reservoir. At this time both the pumps are on (pump in main reservoir, and serge tank).

After the timer for the pump in the main reservoir shuts off, the pump in the serge tank is still on. The pump in the serge tank continues pumping all the water back into the main reservoir (draining the system) until the water level gets low enough. At that point a second float valve shuts off the pump in the serge tank.