Why are they yellow?

Is this from to much light? They are in 7 gallon grow bags fox farm soil, under a 600w hps. The temps are a steady mid 70's during the day and mid 60's in the night. The light is about 2 feet from the top of the plant. This is Purple Urkle from clone, it had roots when I transplanted. Both have a light green appearance.

might need lime,or nutes,over watered.never vegged with a hps before.

First check your Ph. If its ok I would consider adding some nutes.

have you checked your PH?

Not yet. How should I go about checking it other than a heavy water?

Fuck PHing water. Use rain water, that's what I use.
Though you may still have to PH if that doesn't apply to your situation.

I know my house has about 6.5-7.5ph not sure about ppm. Ive never had a problem before with Ph and this soil combination.

i jus use filtered tap water. fox farms soil shood alrdy b ph'd so i dont think u need if u jus recently transplanted. have u gave nutes yet?

That's odd that the light green color is evenly distributed over the entire plant, without any darker areas. Hmm....is it possible that it's a characteristic of that strain? FF soil is very rich in nutes, and PH balanced, so there isn't much chance that it's a deficiency, unless you did something to change that. That soil also has quite a bit of perlite in it, so i doubt that the roots are drowning. Hmm...tough one. I'm guessing that it's the strain type causing the light color. It's definitely not from too much light, if you have it set at 24". You should bring it down to about 16-18", because the light get's fairly weak at 24".

Thanks for all the help everyone. Next time I water Ill check the ph. A friend of mine has 2 of the same clones from the same dispensary and his are a bit darker in the same soil. I do remember the outside roots being a bit brown when I transplanted but I figured she was getting rootbound and this would help. Hopefully the color will come back in a few days, Ill try and keep this updated till I figure whats up.

So the yellowing was from malnutrition. After a few days her top growth turned green and the rest of the plant is still coming along. It took the roots a few days to leave the root ball and stretch out, should have broke up the root ball a little before transplanting. Thanks for all the help.