My indoor system started out with a gravel bed. After repairing a leak in the 45 mil EPDM liner of that grow bed, I decided to go with a Deep Water Culture (DWC) raft. With only one 10' wall glazed my grow bed is 30"x10' long which is a rather small 25 sq ft.. I found it easier to utilize that precious space with a raft system.
|A panoramic view inside grow room. 800 gal fish tank on left grow bed on right|
But loosing the large media bed meant that I would also lose the filtering capability of the 3/4" rock media. So I decided to build a filter using evaporative cooler pads. This works great at first, but after a few months the fish population began to grow and the fish got bigger. The filter could no longer keep up with the poo. Cleaning filters everyday was more work than I was willing to do.
So I decided to return part of the bed to a gravel media, and keep the rest as a DWC grow tank.
|The DWC tank with gravel to the right of a plastic fence partition|
At this point I began to have concerns about a continuous flood gravel bed. RupertofOZ was kind enough to dispel my fears by pointing me toward a very good experiment done by backyardaquaponics.com.