Is my light too strong?

Hey everyone. I know this sounds strange but I am thinking I have "light poisoned" my girls. I have 6.5- 7 week old plants that I put under my 1000 W MH with Sunmaster bulb about 2.5 weeks ago. Before this they were under a 250 MH. Here is what I have noticed. The preflowers started showing about 10 days ago. I separated what I thought were the males from the females at that point. I put the males on the fringes of the lights limits. I left the females directly under the light and even moved them into better position to receive better light. The light has never been closer that 24 inches from the plants. Canopy temp is always between 70-75 RH 55%. I have noticed the males are a better green and are growing 30% faster. Same food, same everything. Always ph of 6.3-6.5. I feed FF. The males reach for the light. The females dont quiet do that like the males. The males are the best looking plants in the room. Color, growth, etc. The females are just not thriving like the males. What do you guys think? Thanks for looking.

need pics to help...

raise it to 30 -36 inches and they will surprise you

Thanks Kite High. Its at 32" now. You live and learn.

Well first thing came to my mind is often (usually) the males will stretch out and get bigger quicker than the females. I don't understand why they would be a lighter shade of green but the 30% growth difference is to be expected in a way: They are males, reaching for the light. Or having to reach more for the light then the favored girls directly under. Growing outdoors from reg seed in years past I seemed to always pull up my best looking plants, height and foliage-wise, cause they were males.

I've never run a 1K and I don't think you mentioned air cooled hoods or anything but I think 30+" is quite a distance away to be getting light damage. There is a big difference in heat damage, and light bleaching/damage.

As long as there is no bleaching or damage from heat they should be fine, as far as the light goes. The sun is way more powerful than anything we can bring inside. Your temps sound right, maybe having such an intense light so close they just aren't stretching for it. I wish I could run a 1000W with those kinda temps. Males will stretch like a sum a na bitch. Are they all the same strain? Is it getting colder than the 70-75 at night, I've noticed that will def slow down alot of strains, especially after a nice warm day under a 1000W lamp. What kind of ventilation do you have, how much air is moving in your grow? out.

Kite High said:

raise it to 30 -36 inches and they will surprise you

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quote the "scientist": If you back the light up to 2', then you lose 3/4 of the lamps energy, a 1000w light will only put out 250w of usable energy at 2 feet, its called inverse square law - its just the physics of light.

he suggests 600 watt lights being more suitable for growing. 36 inches?err sorry, 32 inches??

GW PharmaceuticalsSee how high the lights are? I'll go with these scientists that grow and not a slave to a lighting company.

GandalfdaGreen said:

Thanks Kite High. Its at 32" now. You live and learn.

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As they grow get closer until they slow down again and then add 6 inches and you will know what THOSE plants like in YOUR garden

I keep mine as close to possible watching where the light spreads on walls, I run a 1000w , 600 and 400, all for fkowering, just took down the 400 to replace with a top of the line unit, huge difference in the hood and wallet but well worth it just by looks.

As a good rule of thumb, you want between 40-50W/sqft.

So if you have 1000W HPS, you want to set it up so you have 20-25sqft total canopy.

That means you have to keep the light far away from the canopy so that it covers 20-25sqft.

It's all about canopy planning. Doesn't matter how far or close your lights are as long as you plan your canopy to have around 40-50W/sqft.

Obviously you have to move a light farther away to increase the coverage area, or closer to increase the W/sqft.

note the roof. so I guess the inverse square law is out the window when we're growing weed.

It's not out the window, it's just that if a 1000W lamp is too close, you are getting too many W/sqft. You could have a larger area canopy instead. Light isn't attenuated/lost much because you're farther away, it's just dispersed over a larger area, according to the inverse square law. If you pull the light away, you'll get more area coverage, but less W/sqft.

By this logic, it makes sense to put 400W lamps closer to cover a small area and the 1000W farther away to cover a large area.

dbkick said:

note the roof. so I guess the inverse square law is out the window when we're growing weed.

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Thank you for pointing that out... its obviously a green house those lights are used as supplemental lighting I do believe which would explain why they're so high. I keep my lights as close as I can without temp becoming an issue.

Oops wrong thread

dbkick said:

note the roof. so I guess the inverse square law is out the window when we're growing weed.

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yes note the roof as the UK is so famous for its bright sunny days...and extremely long summers as well


ok mr I know a light engineer and he said.... I get it .... troll someone else...you'll starve with me as I won't feed you

pointing out the facts just really gets to you for some reason. whatever man.

This message is hidden because dbdick in on your ignore list


That is just awesome

Kite High said:

yes note the roof as the UK is so famous for its bright sunny days...and extremely long summers as well


ok mr I know a light engineer and he said.... I get it .... troll someone else...you'll starve with me as I won't feed you

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those lights aint doing nothing but blocking the sun.............they probably use em for veg

woody333333 said:

those lights aint doing nothing but blocking the sun.............they probably use em for veg

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that and remember the UK is foggy and cloud covered majority of the time...if you look close you see it is dark out there but the room is bright and well lit