you def need some cal mag when using ro water and PBP - 5 ml gal should clear up them rust spots

typical for this def to show at 2-3 weeks in flower

Always add anything with calcium into your water LAST, when adding nutes or water change outs. Calcium and sulfur love to get together, get snuggly- and fall to the bottom of your res, never to be water soluble again, lol. It's called 'flocculation' and it sux.

Thanks Guys. Glad to hear that it is an easy fix. Also am I feeding a enough. My PPM's goes down every time I top off with water.

Motherlode took the words right out of my mouth. Calmag will fix this..I would say your maxed on PPM at 1200..when you add water you dilute the strength of the mix thus lowering your parts per million of nutrient to water...

adding water will also change your pH.

I have always been told to do the pH last.

KISS!
If it were ME (the great qualilfier lol)...I'd reduce your solution strength a bit and lose all the additives (except CalMag).

yes, adjust pH last...and check it often. Some fluctuation is ok (good) a lot is VERY bad.

I find that when I use a basic 3-part main nute system (some companies have 2-part or even 1-part) with RO and CalMag (and SM90 alternating weekly with Zone), my plants grow themselves.

It's kind of uncanny. My wife, who has a permit but doesnt like to smoke can tell instantly if I tried something new and I get in trouble every time...and she's right. NOTHING has ever dramatically improved my results. I still give em a shot of homemade MOAB at week 6 though...shhhhhhh.

Do some reading about nute strength or ppm or ec "equilibrium". When you get the hang of that it's the plants telling YOU how many ppms they want. It's cake from there bro.

I think that if you did a poll (and there are plenty of "decent" A/B tests with additives) you'll probably find that other than the people who see the emporor with a suit on, MOST growers (the honest ones) will tell you that 99% ..if not 100% of additives, boosters, sweeteners, swellers, puffers, exploders.......don't do much at all.
You'll ALWAYS get better results by doing things like cleanliness, adding light, ventilation, temp/humidity control, pest control, pathogen (above and below) control. Without those things optimized...you're probably not only throwing money away but maybe even doing more harm than good for your plants by using additives.

All that "important" stuff is usually just all about getting a feel for things, doing a bit of regular work, and loving your plants JUST ENOUGH.
Good luck and keep reading and asking.