A question for the duckweed experts - I setup a dedicated duckweed tank with a small amount of duckweed that I had quarantined for some time. The plants seem to multiply and spread to the whole tank, which is integrated into the AP system, but they later contract, never getting to densely cover the tank. I have not been harvesting the plants, waiting until the tank is saturated, but this is going slowly, and a portion of the plants seem to be dying (turning grey).

The tank has four 100W equivalent CFL's over it, temp is 80-90F in the room, water temp is ~85F, and humidity is ~70%. So what is keeping the duckweed from flourishing?

Roger,

Don't mean to hijack your thread, but figure that this is inline with the topic and the answers may be helpful to more than just myself.