Web like substance forming?

So this is my second time growing in dwc hydro and I have 6 seedlings. I have them all in a single 5 gallon bucket in 3 inch net pots and I have the whole surface of the lid covered with lava rocks and I moved some of them and around the rock wool there was a bunch of spider web looking stuff forming and I was wondering what that is. I don't believe it's root rot or anything had a little trouble with that last time but I keep the water pretty chilled to about 65 usually. Could it be beneficial bacteria? I'm using advanced nutrients sensi grow, voodoo juice and tarantula and I am also using earth juice catalyst and micro blast
 
Yeah I checked them all they're all only 12 days old so they're pretty small not very many places for them to be and I spay pretty much everything down with a organic poison i forgot what its called I even did a light mist on the top of the rocks just to be safe and I use some stronger stuff around the grow area
 
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