Bubbleponics Res - Brown Granules?

I am about 2 weeks into my first grow and, after having no issues initially, I suddenly have a "problem". When I replace the water the last two times, it was clear. I replace the water on 6/24 and now I have brown-ish water, along with fine brown granules in two different reservoirs (filled separately). pH was 6.1, and I am using about half the recommended about of Flora Gro, Micro, and Bloom because I am only two weeks in. This time, however, i added Hydoguard as well, so I am thinking it may be that.

Roots and plants look ok, but want to make sure I don't ruin anything.

Thanks for any help.

Did you thoroughly wash your stones before using them? Kinda looks like stone dust. But it's hard to tell.

That was my initial thought (and may be correct based solely on the color). But because it didn't show up in the first two fills, I didn't think it was from that. But it sounds like its nothing that is obviously bad.

Thanks.

Could be nutrient precipitation. This can be avoided by replacing the side draw pump with a bottom draw pump