Possible PH problems... halp?

Hey guys, I'm running hydro in a drip feed system. for about a week now I've been having trouble controlling PH, and one of my 3 plants is suffering greatly. ph has been fluctating between 5.5 and 7, tending towards 7.

Heres some pics of the chronic, and a couple of the White widow, which is right next to it and totally beasting.

well to temporarily fix this problem you should folair feed your plant. mix up some nutes at like 1/8 strength, add some epsom salt then spray your plant when its 70F and below. make sure to spray the bottom of the leaves, spraying the tops doesnt make an impact really.

and fyi the first 3 pics look like mg defficiency... but because your ph is unstable its probably a lockout problem

Mg deficiency was what I was thinking as well, so I assumed it was lockout. My water is very hard. It also started at the bottom, and I was under the impression that micro nutrient deficiencies usually start at the top of the plant, where as primary nutrient (NPK) starts at the bottom as the nutrient moves through the plant more readily?

EDIT

mg gets locked out at low phs though. potassium and phosphorus might be getting locked out since my ph is pretty high =/

any chances it could just be straight up nute burn?

yes, only you know. we can only give you possibilitE's

I'm assuming its a combo of the both. This is the first time in 4 grows I've had issues like this/to this magnitude, as such just looking around to get some more experienced eyes on the issue.

Um 7.0 is too high for hydro. Buy yourself some quality ph down and it will help to keep the level stable. I would do a swap and add 1/4 strength nutes and some cal mag for a day or 2. then resume feeding as normal.

yeah, I'm aware that 7 is too high hahaha. Ph is brought to 5.8 after I mix up a batch of nutrient, it sits for 3 hours, and I make sure it stays the same. after being added to the rez, over course of the next few days I start to see that fluctuation up towards 7. keeping it at bay with ph down is a fruitless battle it seems.

I'm going to swap the rez and run 1/4 nutes as you have recommended.