Another Newbie Needs Help!

I first posted the pics here.

https://www.rollitup.org/marijuana-plant-problems/150004-plant-moisture-stress-symptoms-solutions-172.html#post7423369

Leaves are turing yellow and curling up! Please help! Thanks in advance.

Here are some details:

bagseed germinated in paper towels moistened with tap water. planted into fox farm ocean forest cut with 25% perlite and a little dolomite lime. sprouts put under 2 four foot long floros until 1" - 2" tall, then moved to 600w metal halide in 2'x4'x5' mylar tent with 240 cfm exhaust fan. temps stay at 79F for 18 hours of light, then drop to 70F for 6 hours darkness. humidity 25-40%. watering with straight tap water that has set out for several days and adjusted to ph ~6.5. no nutrients yet as i am relying on the fox farm to feed them for now. i thought i was over watering but i let them dry out and they didnt seem to get any better. see the pics at the link above. upper green leaves are droopy, growth has slowed, lower leaves are yellowing from the tips inward. lower leaves are also curling up and inward, starting to show a hint of orange/brown leaf at the worst parts at the tips of the yellowed leaves. i will get better pics up soon. thank you!

wow, sounds like you have alot going on! im sorry this is happening your first time, but hey you gotta start somewhere, dont get discouraged! I think you can get alot more help with a better quality picture or maybe just a few more. But Based on your one picture and your description, im gonna go ahead and say it has something to do with your soil. if you're not feeding it nutes already with your water (which you shouldnt yet), not overwatering (making sure your soil is completely dry at least an inch or more down before watering, not just one time, but between every watering). My last 2 guesses having to do with your lighting would be your 600w light is too strong for your plant, maybe try raising it up quite a bit and monitoring its progress, 600w for one plant sounds like overkill. Or that Switching from your florescent lights to a very strong 600w MH shocked your plant and then your efforts to fix the problem is just making it worse. UNLESS your soil has some type of time release nutrient (garbage) idk ive never used fox farm. But I would just raise the light quite a bit, regulate your watering more, and see what happens. This is all i can really say for now based on the picture, maybe theres something on your leaves that could tell me more, but for now thats all i have for you my friend. best of luck!

Thanks for the info. I have been asked by others "Is 600w too strong for seedlings?" and I don't know the correct answer. In my case, it seems to have been too much. Or, I simply pulled the newbie move and over watered. Possibly a combination of both.

Yeah i mean ive never used anything over 400w but i put 3-4 plants under my light so i can only imagine what 200 more watts would do. i would just try to raise your light in the begining and see how your plant reacts as you move it closer. but you could always look into a dimmable ballast and that might help with your problem as well. let me know what happens with it!