How high do i hang my 400w?

[MrMcBean]

Hello,

I got a 400w lamp going on 9 square feet.. or about a cub meter. I want the light to shine everywhere, but i want to avoid the stretch as much as possible.. how far above the tops should i keep the light?
Is there a guide to go by on this?

i should get a 600 for my space anyhow...

~peace

 

[FreezerBoy]

Technically, an HPS chart but, it should give you some idea. Get as close to the canopy as you can without burning and as far away as needed to give all plants full access to the light.

 

[wills43]

That chart is pretty neat.

MrMcbean - The gap should be as close as possible like freezerboy suggested. However, how close you can get depends a lot on your growroom/cab design and how effectively it removes heat. The better it removes heat, the closer the light can get. Many growers hang a therm. at the canopy level to check the temp. I'd say you can get away with a 400w with a decent exhaust fan. A 600w will be better for the square footage, but might require an aircooled reflector.

If you already have a 400w, just go with that. No need to spend more if the results will satisfy. I've seen grow diaries where the 400w are as close as 7", and as far as 12". So that might be a good roundabout figure.

Also, don't forget that in the beginning stages of plant growth you actually start a little high and slowly lower the lights down to let the plants break in. Then you start raising it as it grows.

Hope that helps

 

[MrMcBean]

Thanks for the assuring answers.

FreezerBoy: The chart looks interesting.. but is it really still an "optimal range" to have a 400w at 63,622 inches as the chart suggests? or am i reading it wrong...

Wills43: The cooling seems not a problem. i got a temp below 25 and around 27 at the tops with the vent at 1/4 power .

I have 2 friends... one offered me his 600w lamp/equip and the other offered his 400w which i could add to my current lamp.

all "free of charge.. lol" they smoke enuff as it is.. >< im just afraid of the bill... i guess 1 600 would be ok.. but would 2 400 not be better? hah.. cant make up my mind

My grow btw: 2 Thai haze skunk, a Durban Poison (HUGE) and a ww cutting. All are in the 4th week of flower.. This is gonna get big lol.. (Hydro Bubblerbuckets). They all had 3 weeks veg.. but only under a 15 watt cfl alltogether lol.. after 12/12 under the 400 they just bursted..

 

[Hazeseeker]

I usually keep my 400w HPS around 12-15 inches at most, depending on what stage of the grow i'm at and the current temps inside there, sometimes around 10 inches in veg with a fan blowing at the light, wouldn't like to get any closer than that tho, especially in the flowering stage

Peace
Hazeseeker

 

[snookster]

I do not use a reflector on my 400w HPS at all. Read a thread a ways back about a guy doing a "verticla grow" and tried it. Works great! My light "hangs" from a bar across the top of my closet and the light is EVERYWHERE! My distance is about 8-10 inches away. Constant fan...and I have temp. controlled from outside.




My BIG Sativa baby! Had to LST her....buds are really big now...chopping her in 2 days.:-(

 

[FreezerBoy]

a 400w at 63,622 inches

63,622 inches? EEK! Actually, that's the Lumens ratings at 6 inches. Distances are in green on the left. Again, this is supposedly an HPS chart but, the range it suggests, 6-21 inches, is a great place to start. While Lumens aren't the be-all and end-all we once thought, the light yellow field will give you an idea of how much intensity each inch of distance will cost you.

I'd start at 6. Stick your hand underneath at canopy level and leave it there. Is It too hot? Then you're too close. Is the entire garden under the lamp's footprint? If yes, you're golden. If not, you're too close.

 

[snookster]

Freezerboy is right. Put your hand around by your plants...HEAT? Too close...NO HEAT? JUst right....like Grandma's porridge!

 

[MrMcBean]

Alright. so i assume the results wont suck if i keep the light at 12-15 inches. At 12 inches it seems to spread nicely! but the buds on the side will still be 15 or even 20 inches away depending on their height..

Logically thinking , i plan on getting the 600. for just 200 watt more it gives 2x the lumen of a 400.. thats like hanging it twice as high.. or the opposit of that..

Thanks for the chart. Very nice info about watt/lumen ratios.

Finally i can sleep at night!

Snookster: That sativa is looking awesome! Are u sure she is ready? i was just looking at the white hairs.. Ive LsTed the heck out of mine.. shes a wide S shape and not stopping.. I love it! I lost my digi , gonna get someone elses soon

~peace

 

[snookster]

MrMcBean....My baby is NOT ready...could go another 2 -3 weeks most, but I have company coming that cannot see this or smell this. I am FUCKED! HEHEH but in a good way. She's been growing almost 5 months now. I veged her 1 mo. too long, but that's in the past. Today she has FAT ASS BUDS partly due to the Molasses I have been feeding her. She's a healthy thing and one I can be proud of. Don't wanna let her go, but gotta. Best of luck!! PM me for pics. of the cutting.

 

[FreezerBoy]

Alright. so i assume the results wont suck if i keep the light at 12-15 inches. At 12 inches it seems to spread nicely! but the buds on the side will still be 15 or even 20 inches away depending on their height..

Some people use curved screens in their ScROGs for just this reason. If your plants are loose (no screen, individual pots) rearrange them in the grow every couple of days. Or just live with it, that's what I do.