Hi, I am a Buddhist priest who has two cichlids. One looks so much like this one and the other is bigger and is always chasing the one. The bigger is bright blue all over but slightly faded as they are both new to me. I got them for the children so see when they come to my desk. How can I keep my water stable? These two, one is 2 inches and one is 3 inches long and they live with a plocostomos about 4-5 inches long in a 15 gallon tank with a filter and light. Having trouble with water balance. Thank you. Jo-Ren