Calcium deficiency confirmation?

I've read all the guides and looked at tons of photos and a Calcium deficiency seemed like the most likely culprit but thought I'd try to confirm with some experienced people. This seemed to come on nearly overnight on one of my Kandy Kush plants (I can see this on the majority of the leaves) which is about 2 weeks into flowering. Water + nutes PH read at 6.5 according to the General Hydroponics PH testing drops I used, runoff water came out the same. I don't have the funds for a soil PH tester or other measurement tools.

If this is calcium deficiency (I can't see any bugs apart from garden spiders on my deck grow) would hitting it with Cal-Mag Plus on my next feeding clear it up? Would it hurt to add cal-mag to the mix for the plants I don't see this on as a precautionary measure?

What's your water source? Type of water?

You could add some CM to your water, but don't over-do it. What you see probably won't go away but pay attention to new growth.

Are you in veg or flower? How far along?

Tap water, about two weeks into flowering.

looks like calcium deficiency and a little cal/mag should do the trick. GL

yup calmag imo. i would start with standard calmag then about 2-3 weeks into flowering bump it up to double dose or add epsom if there is any more yellowing.