Quote Originally Posted by keith_r
cool plan for the duckweed feeder, should work ok, you may need to adjust the size of the "shield" to provide more or less feed....is that just "part" of your system? you'll need some kind of solids filtration if you aren't using media filled growbeds
and you'll still need to add a good quality food, duckweed won't provide all the good stuff the fish need
Yepps, changing the size of the plastic shield will regulate how much feed the fish get- this is especially important when there's a lot of duckweed in the growbeds.

This is just the 'duckweed feeder' component of the system. I was planning on having 3 growbeds- 2 gravel and 1 NFT (water is fed from the gravel growbeds). Solid filtration to the duckweed bed is not really necessary- not only is the water being filtered from the gravel growbeds, duckweeds have extremely small roots, and the solids that do make it to the duckweed tank will rarely reach the top.
I also plan on supplementing the tank with an automatic flake feeder (or just manually feed them- the duckweed will allow me to feed them less often- to the point that I do feeding and system maintenance all in one go.)

My biggest issue however, is the growbed to fish tank ratio- add too little fish, and you'll be lucky to grow anything. Too much, and you need a large tank- otherwise the fish may die. There's a lot of other fine tuning involved, mainly in terms of pH. I need something easy to maintain, which is why I'm going vermiponics.