Plants Need Help!!!!

I am a new grower and started my grow room about 4 weeks ago. All was going well until the biggest plants bottom leaves started turning yellow about 2 week ago. Since then the leaves turned up and the plant is dead! This is not what worries me, what worries me is the other plants have started to show same symptoms(bottom 2 leaves turning yellow at edges) and i fear for their precious little lives! It is white widow, i am using a 400 W HPS, i have a fan which was all recommended by an experienced grower as well as the nutrients. However i am totally clueless and have guessed at everything. I water them everyday(300ml each), is that too much? also the PH is about 5, too low???? Please! any help and advice would be greatly appreciated people.

wowsers man your way off! first off water every other day or when your soil is 90% dry. if you water too much then you could risk drounding the toots and killing the plant. PH level's should be at 6.3 to 6.9., you want your water to be just a little acidic. and a 400 w hps can be alot for two or thre plants so keep the reflector an bulb at least two and a half feet away..
i hope some of this helps man,, good luck!
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I think he has you pretty much covered. I only water about once a week. I water till water comes out the bottom. Its very important to let your plant dry out before you water them. You should get some nice size nuggets from that 400 hps. You should try using the Philips Son Argo 430 HPs bulb. Its what I am using right now, its works pretty good for all stages of growth. there is a extra 30% more light in the blue end of the spectrum.

Good luck and cant wait to see some pics....


Hydro#1

yo hydro, thanks for the tip on the 430 watt hps. ill have to look into it. cuz iam using a 400 watt Mh. and there real small and bushy after the 4th week