Using different medium at different depths.

[Zachary Corriveau]

Hi there folks this is officially my first post. I've done a lot of research on AP and noticed that eventually if the ratio of fish to plant life gets too high then solid particles will begin to accumulate in the grow bed often at a rate higher than what the worms and bacteria can digest. I was wondering if you were to use a medium that has extremely high surface area , such as Eheim's SubstratPro, just the top layer that comes in contact with light and water. Hopefully increasing bacteria life. And then make it easier for the worms to move and populate below. Please chime in if you have any advice or ideas. Thanks!

[Jonathan Kadish NYC AA Chair]

Typically all of your media will come in contact with the effluent except the top inch or two. Solids will only be slightly effected by the type of media and the effect of media surface area would only effect the solids suspended in the water column by supporting larger colonies of bacteria. Larger solids would build up near the surface of the media and become anaerobic. The best way to deal with that sort of situation is to have less fish or pre-filter your water with a swirl filter or some other solids settling device.