I have had my crystal reds and blacks for some time now and still they are not breeding, the parameters are all fine. pH is about 6.2-6.4, nitrites and nitrates are 0, Ammonia is 0. general hardness is about 4 dGH (60ppm) and kH is somewhere between 0-1 dKH. I add CO2 for the plants and the plants seem to be happy. I also added a cuttlebone for a source of calcium for the shrimp because they havent been molting. The water temp is about 23 degrees celcius (73 fahrenheit). I am feeding them shrimp food every few days so as not to overfeed them. What else can i do?