Hi Vin,
When you say you want this to recycle your waste I'm not clear on what you mean - I know in greenwater systems in Asia they sometimes use human fecal material to fertilize ponds where they grow fish. I doubt this is what you meant but just in case, we generally advise people not to allow the manure of warm blooded animals into their AP system for disease reasons.
Looks like the feed ratios that you posted are from the University of the Virgin Islands raft model. I believe the media bed numbers I have, came from Timmons and Ebeling but I'm not certain, they would be 25% of the UVI rate so 25% of 60 - 100 gms/ m2. Someone with Timmons and Ebeling's book might set us straight as to the meaning of their media bed numbers.
Vin wrote:
I read about feed rate ratios of 60 to 100 grams per m2 of DWC. Is that possible because solids are removed?
Yes, you absolutely have to remove solids (some pass through anyway, even with the best efforts at removal) with a raft system like at UVI or you get solids coating the roots and causing problems. There's more than one way to achieve the higher feed ratio - you can feed more to the fish you have or you can get more fish and feed the same or less food to each. UVI has four fish tanks so achieving the 100 gms fish feed/m2 isn't really as much of a challenge as it may seem. As far as the fish are concerned you can grow more if you remove solids from the system because those solids release compounds on breakdown that use up part of your filtration capacity. By removing them you gain some production capacity because your bio-filter can still break down all the bad things that would affect the fish. Since most of the breakdown is done by bacteria in the grow beds, rafts or bio-filter, it's really more dependent on them than on the plants, how many additional fish the system will allow if you remove some of the solids. Hope this makes sense to you.
