I've decided against putting a hps in , as im trying to kept the noise levels down , and it means i will have to run 1 or 2 extractors in there if i put a 400w or 600w hps.
So ive ordered a blackstar LED , and i can use my speed controller on my fan , just when the plant starts to smell. that way i can run it at the lowest setting possible that well get rid of some/most of the smell.
I also have 20lts of air being put into the ress through 2 air stones , so its well oxygenated.
I have no issues with ph and ec at the moment there pretty much stable. ph rises .1 over 24 hours. and plant isnt really big enough to make a dent in the ec yet.