Heat stress???

I have 400W metal halide about 3 feet away from the plants, although I have fan and a/c running couple times a day, the heat gets sometimes up to 90 through day and 75-80 night...this plant is the worst from them all, couple of them are looking great and don't have any problems at all...Could this be heat? I tested PH, MG, and couple other things and they all seem fine...had a couple fruit flies but they seem to be gone now. Any ideas please? And thank you in advance!

And I know she looks overwatered I thought its a nute problem at first so I flushed them...( Quess not though

sorry man i have the same problem with temp & i dont know how to fix it..
why isnt anyone replying??

dont use 400w mh for 1 plant its to much go get a low cost enery saving build for a bout£2 from anywear its the right spectrum for all round veg and bloom thay dont give of much heat at all i use a 400w mh for veg and 400w hps for bloom in a room that has 30 plants in on sea of green remember heat rises keep plants low use a extractor to controle excess heat build up and use a inlet fan so outside fresh air can enter room basicly you need to get rid off the hot air your fans are moving not cooling it
step 1 get 2 extractor fans 1 for input air from outside coming in to grow room place near bottom of plants if you use ducting
the secound fan mount it high up near to the lamp use ducting to a hole in the celing or to the outside agiain
this way you maximize the c02 intake from naturel air
try not to use lamps with son-t in them thay give off more heat the standard mh-hps
failing that you could always use fluresant tubes or a vented light hud or more expensive what pro's use is a water colled hps light or the new l.e.d lights thay have vertualy no heat

buy a cool tube hood

I dont have just one plant, have a full closet (about 15 plants), so I will stay with this light...will go with cool air...just wasn't sure if this is really heat stress...?

trust me get a inlet fan see your buds get fatter with the co2 it brings in from outside i personal stole mine from a bateroom i was fitting so try go to a diy store befour a grow shop will be cheaper

also i noticed something else what mediam you growing in looks like grit sand or something very costic like lime

Yah, I would think sand would block the oxygen from getting to the roots? Really dense material that compacts when wet.

sand is technique for keeping the flys out of your soil. the yellowing along the edges looks like a heat issue. i didnt do the cool tube for my first 2 grows and now that i finally have it, it is helping a lot. i just added another exhaust fan. and like above pull fresh outside air or AC air into your room. with an oscillating fan, you should see a change.

sand is good for keeping out fungus gnats.....however I've foung good washed quartz pool filter sand dosen't affect PH other sand can mess up your ph your plants look like they have some ph issues is the only reason I mentioned it....what are you using to test your soil digital pen or soil tester I've been there before my cheap soil tester was wrong got a pen works much better

I just have a soil tester, it shows good PH...these are pics of my other plants - the first one is 4 weeks old, the other ones 3 weeks...they have no problems at all...used everything the same, 50% got yellow and dry, 50% looking great... Will try to cool it down that way thank you!