Actually i have 41 a.bellotti and kind of 6 or 7 Fundulopanchax wich gets BBs two or three times a day. For me it's enough and if i need more BBs, i will put more eggs in it.
Obviously i add a small amount of microworms but just the tip o a knife in each tank to have a little variation for the fishes.
Well, i'm new to Killi's but i hatch artemia for a few years till now and i obviously tried to improve this method. For instance, I add eggs every evening even if the "running" hatch two times to extend the time that I get fresh BBs, I alternate the two breeders, so that one is already one or two days old while the other one is filled up right now, i add half a spoon of natron, the breeders are near the heater etc. etc.
I'm pretty happy with it and i will continue to use this system, without blubber, without brumming airpumps and without current at all.
Roberto, adding air to the breeder can work, i already tried this in the past, (there is a hole in the ledge where you can put a tube) but a lot of swimming eggs and eggshells got in the sieve so i stopped this.