In this video we will see why and how to build a flood and drain system for your aquaponics system.
A common beginner mistake is to build a grow-bed aquaponics without flood and drain system. If in the first weeks it doesn’t seem to make a difference, building a setup without this crucial part is a big mistake. It eventually cause you massive problems. As you know, an aquaponics system is inhabited with 3 main living creatures: the fish, the vegetables and the bacteria. The nitrogen cycle is key in aquaponics and the 3 living creatures play a major role into the cycle of life. As a reminder, the fish are eating the fish pellet and releasing some ammonia into the water. Then, the bacteria are responsible for transforming this ammonia (toxic for the fish) into nitrite and later into nitrate (Plant fertilizer). Finally, the plants are then consuming the nitrate. Therefore purifying the water coming back into the fish tank.
Flood and drain aquaponics
Bacteria biomass is critical
Bacteria activity is key. Without them, the aquaponics ecosystem can’t work properly. The beneficial aquaponics bacteria (Nitrosomonas and Nitrobacter) are “aerobic”. Which mean that they need oxygen to breathe, grow and do their job. In an “anaerobic” (without oxygen) environment, they will simply die. As a result they will leave the room to other bacteria responsible for fermentation. It will release some very bad odors around the aquaponics grow-bed. Offering an oxygenated environment to our bacteria is therefore absolutely necessary to the good health of the
ecosystem.
The best way to ensure a good oxygenation of the grow-bed is to put a flood and drain system in place. A flood and drain system is a device that will allow the grow-bed water level to move from low to high several times per day or per hour. When the water drains out of the grow-bed, the bacteria are in direct control to the oxygen of the atmosphere. Therefore, they are able to breath. When the water level is high, the new water is oxygenated. So the bacteria can consume the oxygen from the water.
2 flood and drain aquaponics system options
There are 2 very common ways to create a flood and drain system. The first one is the use of a bell siphon. I made a special video on this specific topic so I invite you to watch it. The other option is to put in place a timer on your water pump. Place a stand up pipe in the grow-bed going directly into the fish tank. The stand up pipe will contain a little hole at the base. Allowing a little water flow to drop into the fish tank. As a result, the grow-bed will drain when the pump is off. This hole water flow is still smaller than the pump water flow. Therefore when the pump is on, the water flow coming into the grow-bed will be higher than the water flow going back into the fish tank. As a result, the water level will increase to reach the top of the stand up pipe (also called stand pipe).
The main advantage of the timer’s pump technique is the convenience to build. The limitations are that is turns the pump on and off several time per day. It is not very good and generally decrease the pump lifetime. The other negative point is that it doesn’t generate the same flush as a bell
siphon. It mainly drains the system without generating a real flush effect which helps to avoid the grow-bed media to clog with time. The pump on timer system is still a very good option for anyone who want an efficient and quickly made setup.
This video is a key video to understand how to build your own aquaponics system without the bell siphon. It’s the best option for the ones who want to create a setup very easily.
Small scale flood and drain example
Now Let’s go to Europe and visit Andris who has built an aquaponics system in his garage.
Andris is an aquaponics follower and sent us a video of his nicely designed aquaponics system. Today we will analyse the system together. We start the video by seeing 3 growbeds filled with clay balls media.
3 Grow-beds linked to one bell siphon
The flood and drain system is ensured by a bell siphon but the interesting part is that the 3 grow-beds are linked together by a simple drain and only one bell siphon is operating. This is a smart way to link several grow-beds to one system. The down side is that the 3 grow-beds are filling and draining at the same time which can cause some serious water level variation in your fish tank if you don’t have a sump tank.
A small fish tank
The fish tank in Andris’s setup doesn’t seem very large from the video but it is difficult to tell from the picture. Andris is growing trouts and they generally require a significant volume of water (I generally recommend a minimum of 700L). Andris didn’t give much information about the fish growth but I am sure he will give more information in the video comments.
Artificial light
Overall it seems like a very nice flood and drain growbed aquaponics system. The down point is the position on the setup. The garage is dark and the plants need light to grow. Even the fish need a minimum of light to grow in healthy conditions. I generally recommend to cover part of the fish tank to avoid algae blooms but a portion of the tank must offer light to the fish. Growing indoor can be an option but in this case the system requires artificial lights adapted to the need of the plants. Such lighting system has an impact on the general power consumption of the aquaponics system and I would therefore recommend Andris to position the system outdoor or to use low consumption lights such as LED systems. I hope you enjoyed this system review and congratulations again to Andris who is on the good path to success.
You will probably be interested to discover Jonathan’s six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂
