Black spots on roots (DWC)

This is my first attempt at growing in general(DWC) so if I can get some advise/tips that would be helpful!

Earlier yesterday I noticed this black/brown stuff on my roots. My plants are in 2 week of veg. I just started using hydroguard on them 4 days ago at just below 2ml/gallon. Now my question is what is this? I've been looking more into root rott but am not convinced this is it. I also read up on how people use h202 but am unsure to use it if this is not a big issue. I see no way light can be getting in so am curious what u guys may think. My air stones also move water like a jacuzzi so don't believe it can be lack of oxygen.Let me know, I'm slightly worried about it being root rott. Thanks!!

Water temp-70
Ph-5.9
Ppm-330

R u using cal mag?Ripping air stones can do that to the calmag.

myke said:

R u using cal mag?Ripping air stones can do that to the calmag.

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Yea I use cal mag at 4ml/gallon

what nutes are you using

Looks like your root addative or nute sticking to the roots. Its fairly normal, thats more brown then black.

rkymtnman said:

what nutes are you using

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1ml/gallon of advance nutrients sensi bloom A and B
1.5ml/gallon of hydroguard
3ml/gallon of cal mag