DWC having problems

I have used this system for awhile with great results,
but lately I have been getting this whitelike mucus build up
on my roots, not sure what it is.
I cleaned the whole system started fresh, ph is a little high
8.5 but that never hurt them before, when I used ph down
I started having problems so when I didn't use it the growth
was good but now it seem to have come back can anyone help?

I read something about this before.

I think none Hydroponic PH down was the course.

PH8.5 is way to high and it will effect your yeadls big time.
Clean everything, with H202.
and get some good quality Hyroponic PH down.
Hope that solves your problem.
Maybe someone with experance of this problem might be able to give you better help.

DWC seems to work best at PH5.6

That was the first thing I tried, clean with hydro prx.
everything was fine but then,
they all started wilting a few at a time,
did a full flush again and here it comes again
I think it's back to the Foxfarm for me.
Thank you for your help