I tried this exact project last year. I have a 8' X 2.5' tank that I placed under the gutter downspout of the shed at my old house. I added a doz FHM, some lumber scraps for spawning, and would toss in a couple of pellets every day. The tank was in the sun and the water stayed very green. I had to kill the project in early summer when I moved and when I drained the tank I found my original fish and a few doz fry.
I am trying again this year but with a different setup. Now the tank is in a shady area behind the pond dam. I filled it with a siphon hose from the pond then plugged the hose at the discharge end. Anytime I want to add water I just remove the plug, the siphon restarts and I can top off the tank. I fear the fry may have a harder time surviving this time because the shade will result in less zooplankton and I don't know if they can get what the need from nibbling on pellets. Anyhow 12 FHM are in there as of a week ago.
