It's a good thing to have and a must for breeding if your water is hard. You only use the RO to spawn them, the rest of the time it's tap water as usual. You just work out how much you need to wc with to get the tds at around 60-80 and you're good to go. You wait till you see them cleaning and bowing and do a wc with the RO at the % you worked out, a 50% will cut your parameters in half. With your pairing problem a RO wc at 50% might get them in the mood, also wait for a cold front to pass over if you can. In winter here I have to use 30% RO to tank volume, in summer our water is actually a bit too soft and doesn't hold ph well so I have to buffer a little.