gravel bed

[chris marshall]

i'm thinking of including a gravel bed in my aquaponics raft system. Any suggestions or arguments as per the  location? should it be placed before or after the grow troughs. i was considering putting it before the troughs creating more  surface area for the bacteria.

[Vlad Jovanovic]

Before the DWC rafts would seem like the wise choice. As far as the surface area for the bacteria... they would colonize and establish themselves regardless of location...but putting the media bed before the rafts could go a ways in pre-filtering some solids so that they don't potentially start to gunk up the roots in your DWC raft.

Many folks employ the use of composting worms in the media beds to further break down those solids trapped there, and help further release their mineral content. 

[chris marshall]

thanks vlad

[TCLynx]

I agree, media bed after fish tank before raft is best position.

[Tony Harris]

I think it is a good idea!  I have gravel bedgs before my raft beds in a 300 gal. tilapia system.  I have found that putting the  hydroton (or other media) before the rafts helps filter out the fish solids and keeps the roots from getting clogged.  I alos put an air stone in there to oxygenate the water.

I have noticed no slow growth in that bed (lettuce, peppers, cabbage).