Is Anyone Using Phillips 315 Watt Ceramic Metal Halide?

Hi Dogwash,

I'm considering changing out my lighting in my 5x5 tent. Currently using a Mars II 1600 which does great other than the exterior foot of perimeter, for which I put 4' two tube T5s around to improve. Still not doing so swell so I'm looking to upgrade to something that'd do excellent in all parts of my 4 plant scrog plane. Thus, I'm thinking about putting in four 315w CMH fixtures.

Do you think I'm crazy? It's in a cool basement, that 1600 pumps out a decent amount of heat and I've always gotten away with just fans.

I realize it may seem excessive but the goal is "perfect" lighting on all parts of the grow space. At 50w per square foot it doesn't seem unreasonable to me (as long as temps can be managed).
 
Dogwash said:
Wow that's a lot of lighting in quite a small area! My tent is 1.5mx1.5mx1.8m - around the same floor area as you

I'm not sure you would need four 315s, that might be a little overkill

Using two separate single reflectors rather than one double fitting spreads the light out better
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Ya, it would be a lot of light. I figure since one 315w has a flowering footprint of 3x3 there would just be a half foot of overlap between fixtures and in that overlap the combined light would be closer to the quality of full lighting found under the fixture (plus the value of cross lighting between all four fixtures). Since all the 315w fixtures advertise a 3x3 flowering footprint, the math/geometry doesn't add up for full coverage in a 5x5 tent between 2 fixtures (would be more like 5x3 coverage). That's why I'm looking at four. That said, you clearly did well with 2.

This isn't an economic decision, this is mostly a hobby for me and I'm kinda infatuated with using the space to the full potential. I guess I should just buy one and get a sense of it. I'm trying to decide between this or building a killer COB setup. I'm not totally sold on COBs though, despite everyone fawning over it so much these days.
 
Not sure what COB is??

Get two 315s for your five by five tent bro
Don't get too caught up with the manufacturers numbers - one light will spread throughout the tent
Two lights also spreads over the full area but double the intensity
Sure there might b a bit of an overlap but it's a fairly even spread growth wise
With these lights u can afford to have them a good 18 inches above canopy so the rays cover a good area

I'd say one 315 per two plants is a good level

Possibly be a little too intense in there with four 315s

Also b diff to keep temp down under 30c i reckon
 
Dogwash said:
Not sure what COB is??

Get two 315s for your five by five tent bro
Don't get too caught up with the manufacturers numbers - one light will spread throughout the tent
Two lights also spreads over the full area but double the intensity
Sure there might b a bit of an overlap but it's a fairly even spread growth wise
With these lights u can afford to have them a good 18 inches above canopy so the rays cover a good area

I'd say one 315 per two plants is a good level

Possibly be a little too intense in there with four 315s

Also b diff to keep temp down under 30c i reckon
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Are you asking what COBs are? If so, they are the current latest and greatest LED grow light. They're fairly easy to build yourself and there is a new market for kits where the wiring and components are figured out then the customer puts the lights where they want them. Fairly modular technology. You can also easily buy all the parts and build them yourself, if you have a mind to do so. Here's an example Timber Grow Lights

For what it's worth, Sun Systems recommends four 315w fixtures in a 5x5. Personally I do put faith in the stated footprint and find that if anything, the footprint is overestimated but ya, I can imagine that temps would be an issue with 4 in a 5x5 tent.

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I've been researching led but have decided on CMH

I'm running in a 4x4 tent and am using one 6" fan for exhaust and two 10" ducts for passive intake. I'm currently running 780 watts of led without heat issues.

I'm currently looking into the nanolux 630 watt cmh. Its a dual 315 bulb fixture. It is not air cooled and just want to make sure I'm making a good purchase for my tent. I live in an apartment and the central air is not ideal but even so I seem to do alright In. Summer with the 780 watts of led.

Any advice is much appreciated!

If its a good fit for the tent i'll buy it today! I generally have the house set to 78℉. I don't plan on going lower due to electrical costs. Really hope this will work for me
 
Dr Fish said:
If you're pulling 780 watts from the wall now, the heat will be about the same... you may need to run it higher than the leds because of the intensity of the light..
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Makes sense. The higher the temperature, the more light the plants can use - until they hit "the wall," so to speak, at around 86°F @ normal CO₂ levels. One can add supplemental CO₂ and increase the maximum light/temperature a bit.

The particulars would vary depending on strain, methinks.
 
Modular lighting eh? That looks worth investigating :)

Wow ok, I've not seen that sunlight systems diagram before - very interesting, where did u find that?

All I can say is wow, I'd like to give four a go but keeping the heat down could well be an issue - running two i was just able to keep on top of the heat

I managed to pull 1.5g per watt with two 315s out of my 1.5 sq m tent - imagine double that!
Hehe there wasn't much room in there by the end of bloom - Can't think what it wud b like with four

Maybe give two a go? Possibly the manufacturers are overselling?

With your other supplementary lights you wud get a killer crop
 
Dogwash said:
Modular lighting eh? That looks worth investigating :)

Wow ok, I've not seen that sunlight systems diagram before - very interesting, where did u find that?

All I can say is wow, I'd like to give four a go but keeping the heat down could well be an issue - running two i was just able to keep on top of the heat

I managed to pull 1.5g per watt with two 315s out of my 1.5 sq m tent - imagine double that!
Hehe there wasn't much room in there by the end of bloom - Can't think what it wud b like with four

Maybe give two a go? Possibly the manufacturers are overselling?

With your other supplementary lights you wud get a killer crop
Click to expand...

Yes the COBs are interesting but it's still hard to find real information about them other than folks who just bought them and now say they do everything short of curing cancer, I've found. They aren't cheap but their individual components are pretty doable if you buy a little at a time, which would be my plan if I go that route.

That Sun Light Systems "lighting tool" is on their website. I know a manufacturer or vendor wants to sell more all the time but companies get a bad rep fast if they aren't truthful in their advertising. Their purported footprint is inline with what I read folks are agreeing with in practice.

Ya, grams per watt has more to do with the grower than the light but ya, it'd be neat to see 4 in action. I'm pretty set that my next lighting will be very even across the 5x5 canopy so while I may end up starting with 1 or 2 of these lights, I'll definitely end up with 4 or whatever is needed to make it even.
 
Some guy I saw on YouTube can scrog Blue Dream in a 4x4 with a 400w HPS but what was surprising were the size of the nugs. A 315w CMH does just as well if not better than a 400w HPS, so the answer is yes.
 
Nobody will ever convince me to change lights. At least not with what's out. Dogwash killed it. I hit a gram per watt on my first grow ever. I have 2 clones left over that I'm flowering now and there growing crazy. I have been neglecting them somewhat just from being busy and there still going strong. A 315 light in a 3 foot area is perfect. If you have a bigger area get 2.
 
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