Simply cut the RO with Tap water, then you get some GH/KH, otherwise you are just wasting a lot more RO than you need to for a water change.
I only would use RO for fish, plants do not care in 97% of the cases.
So say 50% RO, 50% tap etc.
If you insist on 100% RO, then baking soda + GH booster is a good idea after each water change.