Media filled beds are similar to the trenches and troughs used for DWC. Yet, rather than being filled with only water, so plants can float on the surface, the bed is filled with a growing medium that allows water to flow through and deliver nutrients. Because this growing medium also provides the ideal home for the nitrifying bacteria you need in aquaponics, it is a better fit for this method than NFT equipment. However, it’s still not quite as easy to use as DWC for commercial and large-scale aquaponics production.

First, the media mix does a great job of mimicking soil and providing a strong root growth environment. However, that also leads to clogging. Root remnants and trapped solid waste can fill up all the tiny spaces between bits of gravel, rock wool or any other media used for the bed. Digging out the heavy and tightly packed material, rinsing and tumbling it clean, and replacing it in the bed, takes a lot of physical labor and must be repeated every few months in high density commercial production. This kind of deep cleaning is much easier in the DWC-based system, and even NFT tubes are slightly less work to clean out than clogged media beds, especially after a few rounds of steady fish and crop production.

Media beds do eliminate the need for separate biofilters and reduce the filtration needs for solid waste as well. However, they can be difficult to treat when a persistent disease sets in, which can spread through the water and roots. All those pores and pockets that host healthy bacteria also become hiding places for disease vectors that keep reinfecting your plants or fish after each treatment.

Benefits of Media Beds:

• Act as the biofilter for the system.
• Can handle higher fish stocking densities than NFT systems, but still lower than a DWC system.
• Stabilize water quality changes due to the combination of medium water volume and the buffering effects of the growing medium.
• Allow for strong root growth for larger plants that are hard to grow on rafts.
• Work well with constructed wetlands for additional natural filtration and water processing.