WolfenHawke1: Aquaponics Grow Beds and Media Stackup

Aquaponics is the raising of fish (for food) and recirculating the water through grow beds to grow vegetables (for food). The ammonia that increases in the water in the fish tank is converted to nitrite and nitrate through the same process that occurs in a successfully operating fish tank. In a display fish tank, this conversion occurs in the media in your filter and other areas (under the sand). It is important to note that your fish tank filter's primary purpose is providing the media for the nitrogen cycle bacteria to thrive. In aquaponics, this media is the material used to grow the vegetables. The benefit of this is that the vegetation gets the nitrates they require directly as part of reducing the poisons in the fish water. Thus you get a closed nitrogen cycle system.

On the post, Freeland-fp100-as-aquaponics-growbeds I noted the Freeland bins that I use for my deep root grow beds. On this post I will describe the stackup I use for the media. The pictures below show a bed with hydroton as the top layer and one with vermiculite as the top layer.

The beds after being cut are 20" deep. The bottom 6" are washed 3/4" gravel. There is a long air stone buried in the bed at this point. This is optional to have, but I wanted to inject air here to prevent any anaerobic bacterial action here. A summary of the stackups I use is drawn below.

In some beds, I use Hydroton for the whole top layer (about 6" total depth). In some I use about 4" of Hydroton and 4" of vermiculite.

The reason for the vermiculite is for seeding directly and for a variety of grow media depending on plant preferences. Fine seeds work very well directly in the vermiculite. I have had success with mixed salad green seeds, as well as tomato and cee gwa in the vermiculite. I have had success with cee gwa directly in hydroton also. In general for the hydroton beds, I start seeds in coconut husk pots filled with vermiculite.

The vermiculite really encourages robust root growth. When harvesting often the top 3" of vermiculite is saturated with root (especially when growing tomatoe) and this must be disposed of and replaced with fresh material. Below is a photo of vermiculite saturated with tomato root. Also is a photo of cee gwa roots that were grown in hydroton.