What does that look like?

I am in ebb and flow, this problem does not occur with GH ferts, but with my DIY recipe. a quick reply would be to tell me to switch to GH but my buds are bigger and better with my recipe even with this problem. I tried lowering and upping calcium, flushing, and what else, nothing seems to help in that particular issue. ppm ranges from 900 to 1300 on NaCL scale which means EC 1.8-2.6 25 days into flowering

What about magnesium? Don't expect damaged leaves to recover.

Calcium deficiency. Mg shows as interveinial chlorosis on older leafs, calcium as general necrosis usually on older leafs. Are you using any calmag? Or tap water? May also consider if you're feeding too much of one nutrient that may be blocking out the calcium. As @somebody1701 said, necrosis won't heal, so if it had stopped progressing since you upped the calcium then the problem has already been solved.

does your mix have high K? too much K can lock out ca. and whats your ph? under 6.2 will not lock out but will slow down ca uptake, and will lockout Mag

Thanks, I always thought it was calcium deficiency but the problem is that i have enough calcium in my tap water and in my recipe. I do have a high K mix it is about 5-4-10 recipe, did not think that the K was excessively high to cause this, but given that i have tried almost everything else, it is the most likely cause from what you guys suggested.