Some kind of leaf unknown degradation...

Hi all,
I am currently growing one plant from a seed of unknown origin. It is growing under a 600w hps light in organic potting aoil and kept at a temp of 70 to 80F. It is 2 months old and 22in tall in veg... Has female preflowers. Most of the lower leaves have this condition going on to some extent(most aren't nearly this bad) and I'm not sure what it is. Pictures are attached. I fertilize about twice a week with the Dutchmaster line. Anyone know what condition this is? I do have what look like gnats living in my soil right now if that is a potential cause.

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Fungus gnats can rob your plant of nutrients if they really turn into a large population. Just a couple and it is not big deal. They did not damage those leaves.

My guess is you spilled some nutrient solution on them if they were really low on the plant. If it is just a couple down low I would not sweat it yet. If it starts to go up the plant, I would get concerned.

I'll keep that possibility in mind and be even more careful with my fertilizer but I don't think it's ever touched the leaves and I'm pretty sure this issue started before I started feeding.

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This is helpful: http://www.growweedeasy.com/marijuana-symptoms