Help needed asap

Ok strain: road runner auto. Set up dwc 5 gal 6 buckets. Air pump ap-100 10,000 gal air stone 5in disc. Lighting 200 watt LED x3. 32" above canopy. Tap water used ph downed to 5.5- 6.0 well I though here is the story something told me to get some 7.01 solution to test ph meter it was off reading was 7.5 in a 7.01 solution so I test bucket water ph was reading 4.9 on some. Plant look ok but growing super slow with highly oxygenated water. This is 3rd week pics will be posted. Water temp is 78. Wish can lower no chiller room temp is 82 humidity 45. Ac running at 70. Fan please running. What could be the problem !?!?!
I use dutchmaster root zone I use rapid root and for nut botanicare kind base grow and bloom.
i really don't even know if my ph is correct if the damn Hanna ph meter is giving me correct reading but my plants are growing so slow I never seen this is it a ph problem should I change out water to what I think is correct ph.

I hope you're using an EWC tea with water temperatures at 78F, that's pretty high.

Wrap the buckets in reflective insulation and put something reflective/white on the tops of the buckets to keep the temperatures down. Also when you add water use cold water to get the temperature closer to 65-70F.

If your meter is reading 7.5 in 7.01 solution, that is your problem.
Fix that first.

Calibrate your meter with 7.01 solution, and get your PH to 5.8 and keep it there.

Tav

I did but I don't know if it will hurt plant if I change it right now

what will hurt your plant is if you don't get it to around 5.8

I am try I doing a drop of ph up every 5 hrs to get ph up slowly I also add some more root zone clean up roots and I have some aqua shield on the way with some cal and mag plus to try help out. With highly oxygenated water I didn't think root rot would come but I guess I was wrong but looking better around roots already back white and not that tan brown color

Not trying to do a Dramatic change in ph and I would hate if I drop to much ph up and it went pass 5.8 so I am doing it slowly but surly trying to get oh corrected but I have heard to with some much air in water ph can change anyone have any knowledge on this ?

Just freaking fix it and quite pussying around with it for the love of anything. Really dude, you got solid advice, fix the ph in one setting. Sorry but had to rant. You ask for help and cast it aside and all its doing is letting the plants get less of what they need if they were in the correct ph. Its a weed.

All fix now. I didn't know can do in one sitting but yes thank u all for advice.

Now keep it there.