At this stage of flowering I would not worry, changing anything dramatically can upset your plants and the worst time to upset plants is during flowering.
pH is best adjusted before using the substrate for planting.
I would be giving some of the paler plants (perhaps all of them) a half strength dose of "grow" nutrients to supplement their nitrogen supply, before the plants completely exhaust themselves. This one off application will not interfere with potency or cause any other maturation issues.
As long as your soil is above 6.0 and under 7.2, your plants will be fine.
pHed water will not change the soil pH long term, changing the soil pH is best changed with lime or dolomite, as these 2 substances have a long lasting chemical altering affect on the soil. Using strong pHed water will just lead to your meter reading the pH of the water and not the pH of the soil.
When checking soil pH it is best to do so after letting the pot sit for 24-36 hours after/since you last watered it, this way everything settles and you get a reading of the soil and not the water you just put in the pot.
Hope this helps, Organoman.