I use RO water from the store! i add calmg also, usually its right about 6.5-7.0 before nutes, ive never really let the RO water sit over night also, i stopped using my tap water after i completely raped an auto, and ive never had a problem using the RO water right after i get it.
I bet you, if you stop paying the store for clean water that you have to put shit back into, just use tap water after letting it sit out for 24 hrs. unless it has Chloramine instead of Chlorine, (then use it right away unless you have extra space to use up) and check it, you'll be between 7.5 and 7.9, and save yourself money on water AND PH UP.
A lot of people use tap water or rain water and have great growing plants.
I'm not saying you're wrong, but I hate seeing people that have only read, not done, and seen people with a lot of extra time and money, in different circumstances, or don't know what they're doing that pay for shit to be removed from their water, then pay to put shit back in the water, and don't get the ratio quite right, and fucks up their plants.
I'm sorry, but I am from the old school method..........
Try the free shit, and pay what you have to from there to get what you want.
Pretend you have a car.....
How fast do you want to go?
That will cost you X amount of dollars.
Period.