This is a past tense system. I ran a barrel ponics system for a long time as a pee ponic system. Then I moved it and added a big duckweed tank and ran that pee ponic too. I personally think this may be the only way to really grow enough duckweed to feed tilapia much but you would have to have a big tank that you can keep leaves and debris out of.
Eventually the barrel ponics system ended up as part of my line of blue barrels growing bamboo as a privacy screen and the duckweed tank became my 300 gallon sump bed, all of that is now part of the big system.
However, I am happy to discuss pee ponics and the aging of humonia for safety reasons and anything of the sort here.