My 1st Grow

Sorry to hear about the damage. Got any pix, Fitzy? I betcha it's fine, but just in case can you give a little more info?

What size containers are the plants in? What kind of fertilizer have you given them? Are you tracking the humidity (if not, you'll probably want to get a cheap hygrometer. They're super helpful)? I'm sure there's other stuff I should ask, but I can't come up with anything else...

Anyway, I'm betting that whatever stress you're seeing is either the first, round leaves (cotelydons) starting to die, or heat stress. The plant usually draws nutrients back out of the cotelydons before they die off, so it might just be that. But temps in your tent sound a little high, your HPS sounds a little close, and you may have to make the area more humid.

Rules of thumb:
-Seedlings are tender and can be very sensitive to light, especially a 600w HPS. I don't use HIDs so I dunno how far away it should be, but I'd guess even 4 feet is reasonable. Try reading up on them in the forums, or start your own thread and ask that specific question. Or just use a CFL to light it for awhile.
-At temps above 80 plants have trouble carrying out photosynthesis unless you pump in extra CO2. Try to keep temps in the mid 70s. This probably isn't anything to do with the leaves turning yellow, but it will make for happier and more energetic plants no matter what.
-Back to humidity. Make sure that your little ladies are in the realm of 60-75% relative humidity. If the air is too dry it makes it harder for them to draw up water and nutrients from their roots, which is just another way of not feeding them enough. They'll DEFINITELY turn yellow if that continues. So get a hygrometer and a cheap humidifier if you can, and you'll be psyched for the difference they'll make.

Sounds like a great setup, though, and I'm sure you'll have it dialed in in no time. Keep your head up brother!

hey bud there in 5 gallon pots with miracle grow multi nutrients waiting on humidity reader and humidifier to come this week.
hope to get some pics up after xmas

ive moved the light to 3 feet 1.5 is the recommended height but felt it was to close and seems better and now every morning when i check everythings ok in the tent theres new healthy green leafs.

thanks for feed back and info very much appreciated bro