Plants dying in new Growroom

I have just started a :leaf:new growroom:leaf: in a cupboard i had spare. I have sealed it with culk and industrial tape and painted the whole cupboard white. I have also put down three layers on thick plastic tarpolen and sealed round it.i have a 400w hps (highpressuresodium) light fitted in the cupboard with just an average 2 speed obscaling fan sitting on the floor witch is on 24 hours a day. The Area of the cupboard is = 5 ft long , 7.5ft high , 2ft wide . the light is currently sitting about 5ft from the ground . with my babbies sittin directly underneath it. this is not my first grow op and done 3 previous to this one with sucsess but this is the first time i have used this room and i am running into problems.i can get my babbies to sprout no problem they grow to about 3 - 5 inch's tall with a fair amount of growth then slowly start to die the tips of the leaves showing first signs by turning yellow then this slowly consumes the whole plant the thing thats getting me is its not happening to all of the plants just 2 out of 3. The bigger plants always seem to pull throw it the only thing i can think is there is not enough ventaltion in the cupboard .I have the lights on a 18 / 6 cycle and it does tend to get pretty hot in there do u think id be better to get rid of my current fan and get an extractor fan fitted to the cupboard to help veltalation beacause im confident of my soil mixture and regularly check the ph of my water.

Thanks for your time ppl:weed:
Any responses will be taken with great appreceation!

"What We Need is Love to Help Weed Grow"
 

vapedg13

New Member
You want fresh air comming in.... a couple of holes cut in the base or lower sides of the cab ......add a exhaust fan sucking your heat out to the top of your cab & a fan insided your cab for constant leaf movment.

You need air ventilation and circulation
 

Brick Top

New Member
Your same question asked in the marijuana plant problem forum has several replies with some possibly very accurate reasons for your problem or problems plus a few questions. Check it out.
 
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