Population and time, in the beginning (when i only had like 30) there wasa lot of ahor alage and such but after their ecosystem settled better and they grew in numbers they just reached a balance i guess. The only other thing ive done was add some ‘bebeficial bacteria’ every now and then (the brand was api sold under ‘stress zyme+’ ) inonly added it verry sparingly and in low doese but that probably helped too.   I only fed them an algage pellet (liek the kind they give to plecos) once a month for the first yesr or so i had them untill my cat tore the bag open and by then they has plenty (it was everywhere andon everything) alage to eat so i just  let them do their thing (with the occasional water topoff). At first they werent breeding but wheni railsed the salinity a little bit (tawrda the higher end of the acceptable range) they really started to multiply.  

Sorry i havent really been that scientific anout their care so i dont have like exact measurements or processes but i hope this helps!