Lost last two crops in undercurrent to brown gunk

I was under the impression that it was root rot because that's all you really hear about in hydro but I'm not sure. The substance on my roots and in my system was never slimy and didn't react to normal sterilization techniques. H202 didn't work, maybe even worse and pool shock didnt help either, this is during the grow.

When I started cleaning out my system tons of thick brown clumps of what I know assume is brown algea came out of my return line. It smells earthy and not so much like a fish tank.

If this is brown algea does anyone have any suggestions on how to deal with it? My understanding is airstones make it worse, correct water temps makes it worse and it doesn't need light to colonize.

This sounds like some horrid shit!?

I have little hydroponic experience, but I remove algae from old-plastic dog dishes with hydrochloric pool acid, it works like algae anti-stick. I doubt that you can use that with the current grow at an effective strength (I don't know), but it's something to remember when cleaning up your equipment.

If it is phytophthora infestans, perhaps you can use phosphorous acid (H3PO3).