Black spots on leaves?

Looks like your are in need of some calmag. But a pH between 7 and 8 is no good. There is a pH range where the plants can absorb nutrients. Between 5.5 and 6.8 is where you want to be within. Personally i like to keep my water pH at 6.2. I mix in some pH down, and test. Mix in a little more, stir, test. And i repeat this till i get my pH where i want it. Sometimes it takes me 10 to 15 minutes to adjust my pH. I do it slowly so as to not cause nutrients to bind to one another and render them locked out to the plants. Calibrate your pH pen. Make sure it's accurate because it's critically important to get it right.

Calibrate pen and correct pH before doing any other changes. Also measure runoff pH to get a feel for your soil pH. Different nutes uptake at different pH ranges. I like mine to bounce between 5.5 and 6.5. Using RO water, you're probably gonna want to start using a CalMag supplement too. That's what looks like the issue is with your plant, but adding CalMag won't help if your pH is running too high.

And if your still running at 24/7 light, cut her back to 18/6

Ph is to high. 6.3 to 6.5 is what you want to get it to. When calibrating pen, go back and forth between 7 and 4 until 7 is 7 and 4 is 4, without having to adjust further.