DWC/SCROG Yellow edges & ends, white puffy ball tops developing - mid/late flower??

PICTURES ATTACHED!

Growing DWC/SCROG style, everything has been going sweet (thanks to the wealth of knowledge on here) but starting half way through peak flower production I started to notice bright yellow patches on the ends and sides of the top flower leaves, but not all of the top (only the tops growing closer to the top of the plant not necessarily closet to the light).

After MANY hours searching I could not find anything that would help so I did it all. I refilled the res with new nutes (roots looking great), lifted back the light (600w) to 24+ inches (was 15) I added some epson salts & I reduced the fert from 1350ppm to 1100ppm. PH is checked at least daily 5.5-5.8, temperature has a thermostat keeping temperature between 22C-28C

I think it may have helped with the yellowing but I could be joking myself.. the big problem now is I notice white balls forming at the tops of my buds and some of these tops are starting to stretch the flower skinny (the rest of the buds underneath are growing are thick??)

Can not tell you how appreciative any help would be.

not too sure looks like ether heat burn on those tips ive had it before when i used to bake my buds under a 600w at 12'' that could be it with the 28-22 swing whats your ventalation setup?

Naturally the leaves will turn yellow at the very end of flowering, but it doesnt look or sound like you're there yet. It your strain a sativa? Sativa buds will always stretch.

and it always stumps me why hydro makes non-serrated bud leaves... Looks great otherwise. Awesome setup.