I don't know what the ppm of the tap water is. I do know I have very, very little waste water from the RO/DI unit. The pH is around 7.2 - 7.4 straight from the faucet
Then you are not getting RO water, because it takes a lot of water to make a gallon of RO water, your filtration system must need to be changed, when was the last time it was changed?
pH of RO is around 5.5 or a little higher.
You let the water sit out for 24 hours before using it, reason why I said use tap water is because your feedings is not complete enough to use RO/DI/Distilled water.
Let water sit out and then right before you are going to feed them, mix the nutrients in and shake.
Also remember to shake your bottle well, the nutrients containers well before using them.
What brand of cal mag are you using?
You can use earthjuice catalyst, microblast, sensi cal, cal mag and some others.
Any of those would be complete or nearly complete micro nutes.
SAme goes for flowering as well as veg.