I'm glad we found that out. Bad news is you can't use your water any more to feed your plants. See, pure water PH is NEUTRAL which means it won't increase or decrease over time. The only way your waters PH can actually increase without the aid of an outside chemical (nutrient, or perhaps rust if its in a metal container?) is radiation. The good news is the radiation has to be limited to your water source alone, if it were atmospheric the plant would adapt to the surroundings - So this outside mystery source is the culprit of your PH issues (if your truly letting your water sit for 48 hours and the PH is increasing, you need to do further tests to your water source.... If however you were blowing smoke up my butt because you thought I didn't know a damn thing about PH as an eletrical engineer, your wrong, chemistry is all part of it )

Chem 101 Water PH - pH Scale

The only way to battle this is to bring in water, I wouldn't trust rain runoff -

As for the repotting - If I'm mistaken and you only repotted once, I apologize - It just seems like there has been multiple potting this week. As to repotting not hurting the plant, that's not actually true. Shaking alone can stress/shock your plant, have you ever seen a plants roots grow THROUGH perlite? (I have) The plants roots attach to the sides of the buckets, in all honesty, if buckets were just a touch more porous, I guarantee those roots would find a way through. So yes, EVERY SINGLE TIME you transplant, you are ripping hairs out of the roots, which can lead to stress/shock and multiple stress/shocks can kill your plant.

Even the pros recommend only 1 transplant. Some even suggest you start in your finishing bucket (I disagree, I think you should start in solocups and then goto 3 or 5 gallon)

Now, I'm here to help. Don't blow smoke up my butt, I won't blow it up yours.