I think this may be a time to ignore some of the common information you read about fish. While it is true that about the most talked about item in fish is the PH, I feel it is way overblown. I feel radical quick changes are bad but I find many fish will do fine and even breed well when they are slowly moved out of their "recommended" PH. I have very hard alkaline tap water and I was somewhat concerned about trying planted tanks and fish together as my fish had always been of the types who liked my tap water.
I fell into a sms122 and wanted to try it as it was all set up. I first went with the high setting of my tap water but over several months, as the plants and tank got it together, I began moving the dial just a touch lower which kept the CO2 moving. Over time I moved my PH from 7.6 down to 6.8 and the plants love it and the fish are breeding.
I recommend moving the dial down just enough to get the CO2 you want and watch the fish for how they feel.