I just tried another way. I warmed the water first to 70F, then mixed the solution. then I tested PH and it was 6.50. I'll check it again in 2 hours, if its +/- .5 I'll use it as is! If not, I'll adjust it down to .650 and wait another couple hours. Might be able to shorten the process a bit. As I have 2 buckets mixed, I'll let one sit a few more hours and check PH. But the key is giving the solution time to reach its PH and that seems to take more than 5 minutes....lol! I think maybe too many of us, myself included, were rushing to use the solution. Raising the temperature also definitely affects ph, shifting it upwards. In fact, it maybe that the majority of the PH swing is temperature related. @62F, this solution usually tests a ph of 6.19!
BTW, I'm using Megacrop 2.0. Similar results though should be seen regardless of nutrient brand