Are you running R/O water
Cause that looks like calcium?
I used 5ml/gal calmag in the beginning with some tap and distilled, it was a disaster. Was diluting a lot and just trying to follow MJ coco nutrient schedule that was not working out. Now its just MFG suggestions with just a splash of diluting if the doses where too impersice and high EC slightly.
I received advice here that I followed but for these, I recently found out about Mother plant A and B and started using that since about 1 week ago. Now it is just nutes and 100% distilled and me and plants are loving it.
The fuzz appeared exponentially and more fuzzy instead of harder to determine in earlier stages.
I used Mycorrhizae and am familiar with the fuzz seedlings and roots can grow naturally and the first comment helped me realize that.
The lining is gunky as heck. It appeared like this almost over night and saw a gnat and as a novice, freaked out that it was mold from not buying and installing mini fans for the bottom area fast enough.
I actually just found more into this same issue on other forums (excessive fuzzing) , with different key words in search. I think it will be fine with spraying the outside lightly with peroxide.
Perhaps it is just salts that the fabric makes look like fuzz or it is fuzz from natural and or added fungus that are good to plant. Would delete this thread if I knew how to. Need to remember these forum search engines for growing are not the same as google.