My 65 gal tank has 2 brown bullhead and 2 sunnies. The sunnies are either Ozark Missouri Longear or North Longhear or Western Dollar. I started with some of each and have thinned the tank to 2 but not sure which I have left. But I don't think the species of sunfish is relevant to my question.
I've had my tank for about a year and have always replenished water changes (10% to 30%) with about 50% RO and 50% City water. The City water is reported to have 390 ppm hardness (per the City). My API test of the City water found greater than 200 ppm KH and greater than 360 ppm GH.
The blending of RO and City water has kept the tank water KH and GH between 100 and 150 ppm. pH is generally around 8. For simplicity, I'd like to start using straight City water. I assume this will drive the KH/GH much higher. Would KH/GH in the range of 200 and 360 ppm respectively be a problem for these fish? should I continue with the 50% RO and 50% City water?