Lighting in a 48" x 22" grow tent.

I've been using CFL's with much success up to this point, but the time has come to switch to HPS.

Now I have a custom built (by me) grow tent in my closet. Dimensions are:

44"L x 22"W x 64" H

I don't really like the idea of using one 400w because everything toward the outside walls will get a paltry amount of light.

So I was thinking of using 2 x 150w instead of 1 x 400w to more evenly distribute the light intensity. Perhaps 3 x 150 if I am certain that I can control heat issues.

So... lighting experts...

What do you think of the idea?

I'm not an expert but based on your dimensions and what I have read your room recommend light should be 336 watts = 400 watts rounded up. Cool it off with a tube and I don't see any reason why that would be sick.

Your message is a bit unclear as to why you figure the edge of the walls or outside of the walls will get less light? 400 should cover that spread easily no?

I agree with the cool tubed 400 HPS..

That is the route I was headed when I chose the 600 HPS...

My tent is 36x20x60... pretty similar...

I keep the 600 10" away from the tops... 75F.. but I do have a good vent sys.. prob overkill as it was designed to run 2 tents, side by side...

If you are really concerned, which if you are using a reflective surface I wouldn't worry, you can elevate the plants at the ends a bit with a book or two...

Kinda like stadium seating, or bleachers...

The 150 doesn't penetrate into the leaf as deep.... it just doesn't "hit" that hard...

I would recommend my exact set up, since we have the same dimensions...

600 watt HPS in a 6" cool tube...

170CFM 4" fan dedicated to the cool tube...

440CFM thermostatically controlled exhaust fan...

440CFM thermostatically controlled intake fan, speed controlled to 330CFM...

Small circulating fan inside...

Hope this helps...

Cheers....

flamdrags420 said:

Your message is a bit unclear as to why you figure the edge of the walls or outside of the walls will get less light? 400 should cover that spread easily no?

Click to expand...

Diggitydank is alluding to "The Inverse Square Law" (of light). Roughly stated, it's "As light continues to travel, each time the distance is doubled - the energy is reduced to one quarter.". By the time the photons reach the end wall (theorhetically 22" away), there ain't much energy left! Conversely, "If the lght only has to travel half as far - the conserved energy is quadrupled."

This is just one reson why multiple sources of light are almost always the better option (especially in, relatively, long - skinny areas). Two 150 watters should give you way better coverage than a single 400. Three 150 watters would be off the hook, way better than a single 600! Even though the smaller bulbs have a lower lumen/watt rating, the closer proximity more than makes up for it! Do the math!

OK right on. That totally makes sense. But also though and please correct me if I'm wrong as I'm still totally learning, is that if you keep the large bulbs cooled such that you can keep them closer, then they would be better no?

flamdrags420 said:

OK right on. That totally makes sense. But also though and please correct me if I'm wrong as I'm still totally learning, is that if you keep the large bulbs cooled such that you can keep them closer, then they would be better no?

Click to expand...

That's the beauty of the idea... it's just a 150w bulb, heat is 3/8 of a 400w. You can put them down closer.

Sorry guys... I hate to be the one to disagree...

I keep my 600 watt HPS 10 inches from the tops...

And you are telling me that 3x 150 HPS will give you better coverage and intensity...????

My bulb is almost as long as my tent... no coverage issues there... at all....

and yes you may tell me that the end plants are not getting as much light, but they are still getting more than the Sun's worth...

I believe you have a point in some situations.... but not in small tents...

A larger, cool tubed light will give you a much better bang for the buck...

I say this having run small HIDs, and now comparing to the 600...

In the end though, it's always best to go with what you know....

Best of Luck...

Disagreement is healthy. Where do you get a nearly four foot hps bulb? Due to a bulbs geometry, it is best to orient it perpendicualr to the closet specified, if using a single bulb. However, no proper ducted reflectors exist that allow this in a 2 x 4 space. Trust me, these are the dimensions of m closet too. I've had the luxury of testing many reflectors with a par meter, and found none of the inline reflectors offered even coverage at the ends. Putting any of them ten inches from the canopy was where it started to drop off at the ends actually. Granted I used a 400, but I was uncomfortable with the efficiency of my space. I opted for a light rail and run the ducted reflector six inches from tops. Due to 150's "punch" , two 250's vs. three 150's would be preferred IMO. But there really are more ways to skin a cat. If you can cool with the 400 and no ducted reflector in that space, adjust a wings are getting great reviews, and the sls sungro allows crude venting but great adjustment if you want to put the bulb perpendicular to the closet.

T.H.Cammo said:

Diggitydank is alluding to "The Inverse Square Law" (of light). Roughly stated, it's "As light continues to travel, each time the distance is doubled - the energy is reduced to one quarter.". By the time the photons reach the end wall (theorhetically 22" away), there ain't much energy left! Conversely, "If the lght only has to travel half as far - the conserved energy is quadrupled."

This is just one reson why multiple sources of light are almost always the better option (especially in, relatively, long - skinny areas). Two 150 watters should give you way better coverage than a single 400. Three 150 watters would be off the hook, way better than a single 600! Even though the smaller bulbs have a lower lumen/watt rating, the closer proximity more than makes up for it! Do the math!

Click to expand...

I've been recommending 2 - 150w HPS to a friend with a similar space; 2x 150s would be ideal.....3 150s would be too much heat.

I would take 1 600w over 3 150s all day.

...... because the space is about 2 x longer than it is deep, multiple lights would be better. If it was 3' x 3' Id say go with a 400.

Landragon said:

Disagreement is healthy....

Where do you get a nearly four foot hps bulb? ...

there really are more ways to skin a cat.

Click to expand...

I agree!!! lol..!

No 4 foot bulbs here... no four foot tent either... my set-up is 36" wide... and I said AlMOST...

Sure man.. everyone has the setup that works for them, hopefully, I just cannot see 3x 150 give you the same, or even comparable results...

Best of Luck to us all... lol...

GypsyBush said:

I agree!!! lol..!

No 4 foot bulbs here... no four foot tent either... my set-up is 36" wide... and I said AlMOST...

Sure man.. everyone has the setup that works for them, hopefully, I just cannot see 3x 150 give you the same, or even comparable results...

Best of Luck to us all... lol...

Click to expand...

Are you comparing 3x 150w to a 400w? 3 x 150 = 450; that's more wattage than a 400. Then you take into account the footprint and multiple angles and, yeah... it's a no-brainer. You'd have to put a 400 on a light mover before it could out perform 3 - 150s.

TheFaux said:

Are you comparing 3x 150w to a 400w? 3 x 150 = 450; that's more wattage than a 400. Then you take into account the footprint and multiple angles and, yeah... it's a no-brainer. You'd have to put a 400 on a light mover before it could out perform 3 - 150s.

Click to expand...

I still say that the intensity is different...

You will cover more area, but with LESS INTENSE light...

400 watts and above has way more "punch" to penetrate within the leaf... 150 is just not strong enough...

No comparison... I will keep my single 600 watts vs 10x 150 watts... any day....

But this is just my opinion...

Cheers