Flora BLend Question

Ok I just started adding GH Floroblend to my res. I am running 4 buckets (DWC) and my roots have this brown slimy crap on them. I know what everyone is going to say. Its root rot. Its not root rot. I have had root rot and this is not it. When you have root rot the roots themselves are brown and slimy. This stuff here wipes right off the roots and the roots are still white. So my question is there anyone that uses floroblend in DWC and does it cause some build up on roots and on airstones. I also added some GH diamond nectar but not enough to have this kind of build up.

I had the samething happen last go around i used flora kleen and it cleared right up

bump any one else have any info for me.

Ok someone anyone tell me what this crap is. Once again Its brown slimy but I can wipe it off and my roots are nice and white. Here are some pictures.