When I was feeding at half strength the plants seemed better, but it did not have the dark uniform green color I see all over the boards.
That foliage color is strain-dependent. Last year I had spruce-green indicas (almost blue) alongside a yellowish-green sativa--so yellow I named the mom "Goldie." That's just how she grew. She liked her nutes half as strong as the indicas, and liked an 11-hour day for flower, too.

Here's something I already posted about pH:

There's a table floating around on this board somewhere that shows which nutes are absorbed at what pH. (It's different.)

You WANT some drift. High 6's is a bit out of the sweet spot but in my experience, no big deal unless you leave it there.

I had some pH swings in a coco test I did until I added the plants into the experiment. Then everything leveled out.

But if you can knock the pH down to a number you like, and it slowly and predictably swings back up through all the nutrient uptake ranges, that's just about ideal, IMO.
I was responding to a poster who was having wide pH swings using RO water. Distilled water's even trickier. Be aware when flushing with it (I sometimes Cal-mag it, even for a flush) because with NO dissolved solids it tends to suck everything out of your medium. Kinda "un-reverse osmosis."

RO water with only CalMag in it has very little "ionic strength" to it. In other words, one drop of pH-up or pH-down will have a profound effect on your readings. There's no chemical buffer there to slow down the swings. Doesn't take much to tip the balance.

Get yourself some nice hard tapwater and A/B it against how your RO is acting with your pH adjustments. Dissolved minerals make the tapwater seem more "stable."

Or, try pH balancing distilled water. (The less dissolved solids you have, the more wildly your solution will react.) HTH, Hermie
I would advise AGAINST following "bottle directions" for nute strength until you confirm the manufacturer's feeding dosages are intended for cannabis. Many are not, for a variety of legal and regulatory reasons--even brands that are obviously aimed at the cannabis market. Weed "thrives on neglect" and is generally a comparatively light feeder. Especially sativa types (have I repeated this?) Watch the very end-tips of the leaves for crunchy browning-that's where nute burn can be seen early on.