Here we discuss the different designs of aquaponic systems based on media filled grow beds. There are a few basic styles that have been adopted and trialled by many different people around the world, each of these styles has their own unique advantages and disadvantages associated with them.
Firstly there’s two methods of applying water to the grow beds where the plants grow, firstly the continuous flow method, where water is pumped from the fish tank up to the surface of the grow bed. It then trickles down through the media and back into the fish tank. This is one of the simplest methods of aquaponics, however it does have a few disadvantages. The irrigated water tends to flow straight down through the media and then along the base of the grow bed to the outlet, without depositing all of the nutrients into the grow bed. To counter this a grid of irrigation pipes arcoss the surface of the grow bed should be used, so that more of the media gets wet and plant roots can make the most of the water and nutrients. If there is no irrigation grid them most of the media will remain dry and will neither function as a biofilter or growing area for plants.
One of the means of overcoming this problem is to have the outlet back to the fish tank at a higher point and to keep the grow bed permanently flooded to a certain level. This improves the situation but it’s still not ideal, plant roots can become waterlogged, areas of the grow bed can become stagnant and anaerobic, as the flow of fresh water through the bed moves around any blockages. Ideal the media filled grow beds should be moist 90% of the time to take advantage of greater biofilter properties, which enables a stronger bacteria colony, as well as greater growing area for plants, while also keeping as much of the media filled bed flowing as freely as possible without any blockages.
Flood and Drain (Ebb and Flow)
By mimicking the natural cycle similar to waves or tidal surges, we can gain the benefits of having the media filled beds flood and drain completely, allowing oxygen into the root zones of the plants, while also limiting the build up of solids within the grow bed, because of the constant surging action of the water as it floods and drains within the media beds. With the beds flooding regularly, it has more potential for plant growth throughout the entire bed, while reducing the requirement for extensive irrigation grids across the surface of the grow bed.
During trials of numerous systems by many enthusiasts, including various people across the world it has been found that, the advantages of flood and drain aquaponic systems, outweigh any advantages of a continuous flow system. This doesn’t mean that continuous flow systems don’t work. Joel Malcolms oldest system is a continuous flow system, at the time of doing this website the system is about 7-8 years old and still working very well.
Constant Height In Fish Tank – Pump In Sump Tank
This style of system uses a pump in the sump tank that pumps water into the fish tank, the overflow pipe causes the water to flow out of the fish tank, when it exceeds a certain height, and into a grow bed where it drains back into the sump tank. A simple version of this system can be seen on the left, the black pipe pumps water into the fish tank, while water flows out of the white PVC pipe into the the grow bed before draining back into the sump. This system was run with a timer on the pump and a restricted outlet on the drain, this allowed for a flooding and draining action in the grow bed.
|CHIFT PIST systems have many advantages over other methods, and they have a few disadvantages. The main advantage of a CHIFT PIST system, is that it means there is no pump in the fish tank, the fish tank stays at a fairly constant height, and if there’s ever a pump failure or blackout the fish tank will stay full. Disadvantages are that you need a sump tank with a large volume and a short height, to hold the water and you also need a tall or raised fish tank.|
Simple Flood and Drain
This is possibly the most simple method of setting up a flood and drain system. The grow bed sits above the fish tank, water is pumped from the fish tank into the grow bed, then the water drains straight back into the fish tank below. The ultimate in simplicity. If there’s a problem with the pump or power supply the water drains straight back into the fish tank. This style of system is compact and has very few disadvantages, the only minor disadvantage is that the water level in the fish tank fluctuates when flooding the beds. Also the pump is in the fish tank so if it’s only a small pump with limited solid pumping capacity, solid wastes may clog up the pump, requiring periodic maintenance.
Sump Tank Two Pump
A two pump sump tank system works by pumping water from the fish tank into the grow beds, the water then drains from the grow beds into a sump tank. Within the sump tank is a pump operated by a float valve, as the water level in the sump tank rises the pump switches on, pumping water back into the main fish tank. The float valve switches the pump within the sump tank on and off, the hieght that it turns on can be set so that the sump tank retains a good volume of water, allowing a second species of fish, or young fingerlings to be stocked in the sump tank.
There are some disadvantages and advantages of having a sump tank incorporated in an aquaponic system. Generally having a sump tank means that water is pumped back numerous times per hour to the fish tank supplying freshly oxygenated water to the fish. It allows quite a large system to be built without having to dig or bury any tanks into the ground, and it allows for the
|stocking of fingerlings or other species within the sump tank. The disadvantages of this system is that it requires two pumps and, if there’s a power failure, and the grow beds all happen to be full then there’s a chance that the sump tank may overflow, losing water from the system.|
There are a few of simple ways to flood and drain an aquaponic system, firstly a timer can be used to regulate the pump that’s filling the grow beds. A simple way to do this is by using stand pipes, stand pipes set the maximum water level in a grow bed, and excess water that is pumped into the bed goes straight over the top of the stand pipe and down the drain. When the pump turns off water drains slowly from the bed through small holes in the base of the standpipe.
Another method of creating a flood and drain cycle within a grow bed, is by using an ‘autosiphon’. Autosiphons rely on a constant, relatively slow flow of water, into the grow bed. When the grow bed water level gets to a certain height it prompts the autosiphon to drain the bed, because of the change in pressure around the autosiphon. This drains the bed quickly of the water. Autosiphons can be a little fiddly and can be prone to failures on occasion but they are fun to experiment with.
Really there’s no end to the different ways that you can design an aquaponic system, it’s best to begin with a simple system, so that you can get a feel for aquaponics and how it works, before trying more complex methods. Flood and drain methods definitely hold more advantages than continuous flow methods, and the stand pipe / timer method is the most simple to start with as nothing major can go wrong. To see a wide range of BYAP system layouts click here.
Design your own Aquaponics System
Have you got a great idea for an aquaponic system? Want to design your own system or see how one of our BYAP systems will look in your area? We have designed 3D components of our systems so that you can easily design, modify and create your own personalised layout of a BYAP system to suit your specific area.
Google Sketchup is a fantastic tool to use for simple 3D design, and almost anyone can use it without after just a few minutes experimenting. Below are some links to tutorials that will get you started and familar with Google Sketchup.
After installing and running through a quick tutorial you can open the BYAP components link below and use the components to design your very own Backyard Aquaponics system to suit your own yard.