Leaves getting splotches, need help

I have two regular blood orange seedlings here, one looks fine, but the other is getting some kind of pale splotches on the leaves. I'll post pics of both. Help would be greatly appreciated.

The one that looks healthy does look pretty good...you may want to read up on N toxicity though IMHO.
Now, the other one..it does not look deficient to me so I am at a bit of a loss...The only opinion I can really offer is that if this were my grow...I would be thinking critters. But then again only the one plant has the issues. HMMMM...

Well...not to worry there are a lot of growerz on RIU that may have other and better opinions than my own.

I'd go with some form of critters causing that or root fungus. Looks pretty far in whatever it is. I'd be having a very close look at those leaves, particularly the underside for bugs. You can also try some H2O2, it'll kill any root system issues but not hurt the plant. just add 3% solution mixed into your water at 150 ppm. I've used that to get rid of pythium, worked well with a couple of waterings.

I agree the other guys, looks like mite or thrip damage

I'd like to throw in thrip damage as well actually. Just google it, looks exact same!