I am not sure about the low grade CRS/CBS. But I gave some (6) of my S/SS CRS/CBS to my buddy and he breeds them with his tap water and/or sometime 50/50 Tap/RO water mixed. It seem like two of his female are berried right now, not sure if they will hatch successful or not for later yet. But the TAP water in our city is low pH like 6.2-6.4, TDS: 40