400w hps

hi to you all, ive just purchased a new 400w hps light unit but i need to know a thing or 2 before i install it in the grow room. any & all suggestions will be greatfully received. i have looked in FAQ but it doesnt tell me what i need to know.
1. how far above the plants will it have to be so i dont burn my babys ?
2. how many plants would i be able to grow under it if my grow room was 3ft x 3ft x6ft ?

i have only used flouro's & cfl's until now.
cheers
o2

Is it air cooled? Do you have adquate ventilation? If so
Recommended typical OLH distances:

Flourescents: proximimty
400w HPS: 1 foot
600w HPS: 1.5 foot
1000w HPS: 2 foot

1 bush....or 9 plants..*SOG* style would fit in that space and fill it completely. It all depends on how you want to approach it.

250/9 = 27 watts per sq ft.
400/9 = 44 watt per sq ft
600/9= 67 watts per sq ft.

50 wpsf is optimal with an hps in bloom..but you can go higher if the ventilation in your space will keep the temps in the optimal range of 70-80.

mogies light height suggestions are right on. you'll still have to play with it yourself and find the optimal heeight but that is close. Keep in mind that a fan blowing across the/between the tops of the plants and the light will allow the light to be the closest it can possibly be to the canopy.

good luck

bt dt

o2hustla said:

1. how far above the plants will it have to be so i dont burn my babys ?
2. how many plants would i be able to grow under it if my grow room was 3ft x 3ft x6ft ?

Click to expand...

What a surprise another person who can't find what he needs in the FAQ section, no surprise really considering how poorly the GrowFAQ is put together.

1) Assuming the HPS isn't air cooled, a 400w HPS should be kept at least 3 feet away from seedlings and small clones, 2 feet away from younger plants in vegetative growth and 18-12 inches from full size plants.

2) 3ft x 3ft you're looking at a maximum of 4-6 full sized plants.

hi there mogie, btdt & babygrow, thanks so much for your advice. im not using it at the moment but the light is not air cooled but im sure i could rig something up to cool it down abit. the ventilation wont be a problem either as im going to construct a decent grow room with good vents and filters. ive got some plans drawn up to maximise air-flow into & around the plants. i want to go for maximum yeild on 2 or 3 plants so im taking my time to get things right this time as im almost finished my first grow under flouros & cfl's. this site is a great source of information for noobs like myself & without you guys it would not be possible.
thanks again guys.
o2