Root problems! Seedlings - RDWC - need help. Diagnosis? H2O2?

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OK, so here is the roots of one of the plants. I looked at 2 more and they looked similar. If you look close you can see the brownish discoloration on one. It looks like that area of the root has been thinned a bit. This can't be good.
The bottom of the rockwool isn't really wet, and the hydrotons that aren't next to the open area of the netpot aren't really wet either. I don't know if that's a good thing.
Considering adding H2O2 to res in the hopes that if this is a bac or algae, the H2O2 will eliminate them by adding lots of O2 to the water.
Is that ok? Will it harm 10 day old seedling? How much would I add per gallon of the 3% drugstore kind?
Help this newbie, please!

All those views and no help? I said please!

hey, looks ok to me, if your hydroton isn't damp you should probably top feed for awhile until the roots break the bottom of the net pot.

the look fine to me, are u sitting in the hydroton? if so everytime u pull it up ur uprooting and causing stress, and evertime u set it down your putting pressure back on the roots.. just leave it be and top feed until ur roots hit the bottom of the net pot.. as said above..

just dont over soak ur rockwool let it get a light dry to it before watering again