2 X 150w HPs 'Vs' a single 250 w HPs in a verticaly challenged grow room

Would like to know if can get my plants closer to lights by using 2 150w spaced about 40cm spart, Instead of just 1 250w HPs in the middle. I Read that you should leave a cm per 10 watt distance but not sure in this case. Grow area is only about 60 cm high and nearly a meter across. Just finished my first fairly successful CFL grow and I'm considering hps upgrade( CFLs were very close but the overall watts being used were a bit much and the heat was a problem. Thanks for any responses, this is my first post on any forum ever. How exciting

Hps in that small of a place is going to cook things.
24” high is not a lot of room

IMO good quality leds and a good exhaust is going to be your best bet.

4x 50watt COBs would cover nice. Or some quantum boards.

SuperDoobieBrother said:

Would like to know if can get my plants closer to lights by using 2 150w spaced about 40cm spart, Instead of just 1 250w HPs in the middle. I Read that you should leave a cm per 10 watt distance but not sure in this case. Grow area is only about 60 cm high and nearly a meter across. Just finished my first fairly successful CFL grow and I'm considering hps upgrade( CFLs were very close but the overall watts being used were a bit much and the heat was a problem. Thanks for any responses, this is my first post on any forum ever. How exciting

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on top of the heat...hps are fairly large units...even an open wing reflector is still going to be about 4 or 5 inches thick. if you use low, wide pots, thats still about another 6 inches, which leaves you with about 16 inches of grow space, which is about the amount of space you want between your plant and light. So you can grow plants 1 inch high....................get an led. if you can afford it, a decent quantum board from a place like hlg or timber would do you real well in that space. if you're handy, you can buy a kit and save some money, or buy some samsung strips and wire up your whole area pretty cheaply. even a 200 watt (real draw, not "equivalent to") meizhe or (Gasp) mars would get you started, till you can afford something better. i like hps, and it is effective, but there is a minimum area requirement, and you just do not have the room for even one 150, without toasting your plants.

Bridgelux EB strips can be run within a few inches of the canopy...

http://ledgardener.com/diy-led-strip-build-designs-samsung-bridgelux/
https://www.rollitup.org/f/led-and-other-lighting.124/

Anything is going to be a bother with only 2 ft of height. But 2x 150w will be less intense thus could be closer and you would get better spread.

coreywebster said:

Anything is going to be a bother with only 2 ft of height. But 2x 150w will be less intense thus could be closer and you would get better spread.

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true as a statement...but you know there's no way he can run even one in that area without just frying a plant

Roger A. Shrubber said:

true as a statement...but you know there's no way he can run even one in that area without just frying a plant

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Yeah true, cant imagine been able to use a 2ft high space with any light other than lots of blue cfl. I have done that long ago and basically you end up with tiny xmas trees that are 6" tall and yield 6 gram each. Cant think of another light source I have seen do the same.
I think I could work with 3ft height if I was desperate but that's beside the point.

You ever worked in such tight conditions with t5/8 @Roger A. Shrubber? I know as far as efficiency they are far better than cfl
Never personally used them though.

nope, i use t5s in my little veg area, and that gets it hot enough. the space is 3x5x3.5 high, and a 4 foot 8 light fixture will get it up close to 90 if i don't have a couple of fans running in there....couldn't imagine running twice that many in half the space

Roger A. Shrubber said:

get an led. if you can afford it, a decent quantum board from a place like hlg or timber would do you real well in that space. if you're handy, you can buy a kit and save some money, or buy some samsung strips and wire up your whole area pretty cheaply.

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I couldn't have said it better. I would look for a Samsung LM301B led (223 lm/W) or LM561C led (210 lm/W) kit.

I just use only 1 250W..because i dont have any others.

Even Led screw ins will do much better than CFLs and last years. You can also use them around the house when you get a HGL 135 watt Quantum Board kit.

So is their any truth to the 1cm per 10 watts for distance rule? (600w should be 60cm etc) would 250 hps really give out more heat than 700 CFL? my first grow had 700wtts of cfl until I took out 125w to get the heat below 30 when it started flowering but even with a cheepo extracter the heat was manageable (I'm aware the watts may be overkill) also t5s would be better as their a lower profile but are their any other pros or cons? Thanks for any replies

By the time you math in the dimensions of the light, pot and space between the light an canopy, there is no room for a plant. Even with t5 lighting, I don't see anything getting much past a seedling stage in that small a space. I would put time and money into a larger space. You had problems with heat using CFL, a HPS is gonna turn that box into a toaster oven.

So this is the first grow. 4 strawberry amnesia clones. Got about 7 Oz ( a lot more than I expected) had 200w red and 250w mixed for flowering but before that had another 2 125w greenish spectrum lights(5500k) I was hoping to get the heat and electricity bill down but everyone's saying 150 hps would fry the plants.

SuperDoobieBrother said:

So is their any truth to the 1cm per 10 watts for distance rule? (600w should be 60cm etc) would 250 hps really give out more heat than 700 CFL? my first grow had 700wtts of cfl until I took out 125w to get the heat below 30 when it started flowering but even with a cheepo extracter the heat was manageable (I'm aware the watts may be overkill) also t5s would be better as their a lower profile but are their any other pros or cons? Thanks for any replies

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heat is a function of wattage X resistance...if you have a 500 watt hps, and 500 watts of cfl or t5s...they'll produce close enough to the same amount of heat to make no difference to you. leds are slightly different, in that they produce a lot less radiant heat, which is harder to get rid of, than ambient heat. cfls and t5s will produce a lot more radiant heat than leds, but less than hps...so subjectively, the area may seem cooler, but the energy transfer is the same, it's just being absorbed and radiated in different ways

HPS puts off a lot of far red and that includes infrared. This heats up surfaces it hits, including the leaves of your plant. It is my belief that using a HPS light in an area that small, regardless of how much ventilation will still fry plant tissue with the infrared. I just don't see the HPS as your best option.

SuperDoobieBrother said:

So is their any truth to the 1cm per 10 watts for distance rule? (600w should be 60cm etc) would 250 hps really give out more heat than 700 CFL? my first grow had 700wtts of cfl until I took out 125w to get the heat below 30 when it started flowering but even with a cheepo extracter the heat was manageable (I'm aware the watts may be overkill) also t5s would be better as their a lower profile but are their any other pros or cons? Thanks for any replies

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T5's aren't very efficient, that means more watts needed for the same amount of light. More watts means more heat, 1 watt equals 3.42 BTU.

Good LED can give you the same light with half the watts and heat. Also, leaf temperatures run several degrees cooler under LED due to the lack of infrared (radiant) heat, so 27-29°C is best air temperature under LED.

1212ham said:

T5's aren't very efficient, that means more watts needed for the same amount of light. More watts means more heat, 1 watt equals 3.42 BTU.

Good LED can give you the same light with half the watts and heat. Also, leaf temperatures run several degrees cooler under LED due to the lack of infrared (radiant) heat, so 27-29°C is best air temperature under LED.

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which can actually lead to you losing money in cold climates...you have to heat the room to the proper range, instead of just venting it with a fan....EVERYTHING is situational....many people use hps in the winter and led in the summer, or supplement one with the other at the appropriate time of year