how far should 150watt hps be from girls

i know most people say 18 inches to 24 inches but they have like 600 watt hps lights and big grows, i just have 2 girls and it seems like 18 inches is pretty high for such a small light, if anyone has used a 150 watt hps how far did you keep it away without damaging the precious

first of all, some things need to be taken into effect

room temp good bad?

sealed, vented or open faced hood

or is it vertical

do you run scrog, sog, are your plants bushy or single cola do you plan to have mutli-tops?

And to answer to question straight, id say 6-10 in is safe and if your area is well ventilated and cool closer, i run 250 mh for veg and they are always under 10in with no problems

and the rule of thumb is 12 in for a 1k, every 30 cm or 12in the lumens degrade by 50%

Guessing just a few inches - even a 400 you can get pretty close with. A lot depends on how old the plants are - you'll fry them when their young, when their old, you might fry off a leave or two.

officernasty said:

i know most people say 18 inches to 24 inches but they have like 600 watt hps lights and big grows, i just have 2 girls and it seems like 18 inches is pretty high for such a small light, if anyone has used a 150 watt hps how far did you keep it away without damaging the precious

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4-10 inches any more and you are losing light intensity.

where are you growing,closet, cab, room?as long as you have good vent you can put the flowering plants pretty close 3-4 in.and yeah about 10" away and they arnt getting enough light.

thanks for all the input, i guess i should have said but im doing 12/12 from seed right now and im in a closet with a closed hood, the light is hanging horizontal and the temp stays between 77-85, in texas and its been over 100 degrees everyday so its hard for the a/c to keep up but i have a box fan in the door way as an exhaust and i have a tall skinny fan in the closet osculating and i have a small fan on a shelf aiming at the light to keep it cool but i havent turned it on yet, also i have cfls for side lighting and nothing is in the soil pots right now just the 2 hydro