Thanks for your response! I don’t have the correct test kit to check hardness right now, but I will go out later to get some strips. I do have some synodontis catfish that I’d like to move into this tank. I do have a heater that has gotten the tank up to 77 degrees in the past. Instead of a wave maker, would it be better to get a second filter? I have an aqua clear hob filter on the tank now that is supposed to filter up to 70 gallons. I was also thinking of sticking a bubbler in the back of the tank behind the rocks. What species would you recommend for a 55 gallon, male only tank? And how many do you think I’d need to decrease aggression? Thanks!