they will breed faster at 75 degrees but color will show better at 70. do you dose? if you do i'd suggest you to stop because CRS cant tolerate too much ferts. if you dont i'd suggest a bag of purigen, it works extremely well, and it will also take out w/e is harmful for shrimp. are you reserving the whole tank for CRS? because besides catfish, even the smallest fish will attatck/eat CRS fry.