Black Worms, Tubifex, Whatever

Jase, how is this project going? Is it still set up, and do you have any more information to share? I've just set up a small (5.5 gal) tank for this purpose, and I'm wondering how much waste control is required, as well as what kind of population density is sustainable.

I was going to use a hang-on-back filter with the water level in the tank raised up above the return flow to minimize turbulence, and I was thinking a drinking glass placed around the intake so that the suction is very high in the water might be enough to prevent worms being sucked into the filter. Any thoughts on that?

I'm responding to a message over a year old, but what the heck... After buying a new house, I've been too busy to put much time into fishkeeping at all for the past 1-1/2 years.

I don't remember exactly when I took down the blackworm tank, but it was certainly a number of months and the culture lasted fairly well until that point. Because of the sheer volume of worms and amount of food you give them, fairly frequent water changes are required, and that was difficult in my last setup (at my office).

I don't know what the upper limit of population density would be, but I'd guess quite high as long as you have adequate biological filtration to deal with waste. It's pretty surprising how little of the worms you see once they're all burrowed in, but when you give it a stir to bring them all out, you can have a lot of worms in a pretty small space.

I think a hang-on-back filter like you described would probably be alright, but you'd definitely need to be sure to minimize the turbulence of the outflow.