I've been working on non refrigerated blackworms in a long term culture for many months now. Two options seem to work well for me to feed a few times a week.
I feed either a few pellets or a few algae wafers every other day. I pour out the spring water and refill each version with fresh spring water weekly.
Option A
3" of sprig water with chunks of coral and 2x2 squares of scrubber pads for easier harvesting
My testers : Carinotetraodon travancoricus (WC)
Option B
3" of sprig water with chunks of coral and a filter bag of crushed coral for easier harvesting. If i shake the bag the worms segment making new blackworms by division. I havr noticed in this set up they often concentrate to the bottom of the coral bag