Aerating your deep water culture beds is a really good idea for more than just the obvious reason of keeping your plant roots healthy—it also helps keep your system water clear. Introducing oxygen to the trough sustains healthy root development in the aqueous conditions with ideal levels being at about 8ppm of DO or dissolved oxygen. The plants will grow at lower levels, but so will other things potentially opening up your system to disease and other issues. Clearly, healthy plants mean a better harvest with fewer pests and a more natural disease resistance. But also, from a food safety perspective, keeping the beds active and moving is a better way to ensure there aren’t pockets of anaerobic sludginess building up in your system. The sludge buildup can cause a host of problems from increasing BOD (biological oxygen demand) of the system to physically covering your roots and essentially suffocating your plants.
We often focus on the fish as the reason for the filtration in the system, but the plants also have a role when it comes to suspended solids production in your deep water culture troughs. That’s why it is vitally important to aerate your system beyond just the fish tanks. As plants grow, they slough off root cells and produce root exudates through photosynthesis feeding bacteria which grow in the system troughs. Without some form of turbulence in the trough, the organic matter will continue to build up away from the primary filtration in your system.
In our experience, airstones placed every 4 feet in the deep water culture troughs helps to ensure there is enough oxygen getting to the plant roots and also provides enough turbulence to suspend the solids, which will eventually be captured by the filtration to keep your water clear.
Keeping the crud out of your troughs allows you to keep a consistent DO and assists the beneficial biology to stay healthy and do their jobs more effectively providing more nutrients for your plants to grow healthy nutrient dense produce. When designing or redesigning an aquaponics system, make sure you remember to aerate your troughs.