My local water supply has two kinds of RO water. Regular RO and a alkaline RO water. The difference being that the alkaline RO water goes through a calcite filter during its process and the regular does not.
Is there any benefit going with the alkaline RO?
The benefit of RO water is that there is very little in it and as such it doesn't alter PH. Using RO water eliminates one variable to worry about when the plants are doing poorly and makes it easier to see how to correct it.
The alkaline filter will raise the pH of the water for you making it slightly less acidic. I'm assuming the plants will prefer water being closer to 7pH than 5.5 although plenty of people manage to grow nice buds with regular RO.
The alkaline filter replaces the minerals what the RO removes such as sodium (Na+)
potassium (K+) chloride (Cl-) calcium (Ca2+) magnesium (Mg2+) bicarbonate (HCO3-) phosphate (PO42-) sulfate (SO42-) The PH of the alkaline filter will be at 8.5
Last year I used a splitter and a hand valve at both ends, alkaline for me RO for the girls, I did experiment a little bit with seedlings and cuttings, 70% germed out of 50 and the cuttings were in a 5gal mister, the results were similar to RO water just my 2c .peace