What is the highest watts/sqft you have flowered with using CMH?

[JoeBlow5823]

Looking at running two 315 cmh lights to flower a 40''x40'' tent. That will come out to 57w/sqft. What do you guys think? I want to get a really good CMH vs HPS comparison. The other tent is a 5x5 1000w double ended HPS running at 1100w. Obviously thats more watts per square foot for the CMH but they are significantly less efficient. If hps is 30% more efficient then that comes out to basically the exact same w/sqft. I figure both tents are pretty close to the upper limit of what the plants will be able to handle.

 

[JoeBlow5823]

No one? Changed my setup to a 60''x32''x80'' tent. The lights fit better and it comes out to a more reasonable 47w/sqft.

The 5x5 is 44w/sqft so it should be a pretty even side by side comparison. Will also give me a good idea of what 4 315's in a 5x5 would do.

 

[JoeBlow5823]

Well this thread never took off but heres an update. I was going to do 4 strains in this tent but I ended up doing 8. the 4 plants on the left got a good amount of veg time and training. The 4 on the right got flipped to 12/12 when they were about 2 weeks old. they were topped once and should be fine testers for those strains. So far this is an excellent veg/tester tent. at 47w/sqft im seeing no issues with light stress.

 

[Horselover fat]

I ran a 315 in my 2x4. I always thought it needed 50% more light.

 

[Rurumo]

I'm trying out a 630 DE cmh in a 4x4 right now, nice to see a cmh thread. I'll keep my eye on it.

 

[JoeBlow5823]

I ran a 315 in my 2x4. I always thought it needed 50% more light.

yea thats 39w/sqft. my tent is an odd size at 32''x60''. im at 47w/sqft which is more than what u ran but more like 20%. i see a lot of people say a 315 is great for a 3x3 but 35w/sqft is really only enough to veg.

I am starting to see where 4 315's in a 5x5 is a good option but its a lot harder to cool 4 open fixtures than a single air cooled HPS hood.

I have a 5x5 running 1100w HPS so im looking forward to comparing results because they are very similar setups with very different lights.

I'm trying out a 630 DE cmh in a 4x4 right now, nice to see a cmh thread. I'll keep my eye on it.

im curious about those. might look into a 1000w DE CMH bulb if the cmh plants turn out better than HPS.

 

[Rurumo]

My cousin grows killer bud in a 3x3 with a 315, I wouldn't get too hung up on the watts per sq ft-I'm sure you can push it higher, but people are killing it at these levels as well. I'd love to try a 1,000 watt DE cmh, but I have low ceilings in my grow areas.

 

[JoeBlow5823]

My cousin grows killer bud in a 3x3 with a 315, I wouldn't get too hung up on the watts per sq ft-I'm sure you can push it higher, but people are killing it at these levels as well. I'd love to try a 1,000 watt DE cmh, but I have low ceilings in my grow areas.

Oh im sure u can get killer bud from 315 in 3x3 but is the canopy/buds as dense as it could be? likely not. i want those rock hard buds that bust teeth off quality grinders.


as far as height goes....ive got these under 1000w DE HPS running @1100w. tent is 84''. (yes i did a lot of training). the center is just a touch hot, if i ran at 1000w the center kolas would be happier but the outsides would be hungry for more light. a 1000w de CMH would run just fine in my tent; it would honestly be a touch under powered




the setup

 

[Apalchen]

I ran 2 3x3 tents with a 315 in each for years, You have to keep canopy short as they don’t penetrate as well, but got rock solid mugs that were better quality than my other tents at the time which were way more watts per sq ft. Average between 10-12 zips per tent.

i have sense moved and run double ended hps, way easier to get yield from as nothing penetrates quite as well. I still feel the quality of cmh is a bit better, but with lack of penetration you would need more sq ft to get the same grams per watt.

 

[Psyphish]

I ran two 315w D-Papillon fixtures in a 3x4. I felt it was perfect, but if I were to do it again I'd probably add some LEDs, just out of curiosity.

 

[Rurumo]

I ran two 315w D-Papillon fixtures in a 3x4. I felt it was perfect, but if I were to do it again I'd probably add some LEDs, just out of curiosity.

When I read your post I was thinking...this person's avatar looks so damn familiar...then I got it! I was just reading this thread the other day-https://www.rollitup.org/t/630w-cmh-for-a-beginner.964623/
This was one of the threads that convinced me to try out CMH, Growing Jables was killing it! My covid wallet was the other factor-no expensive LEDs for me for a while. Sucks they took your lights!!

 

[JoeBlow5823]

I ran two 315w D-Papillon fixtures in a 3x4. I felt it was perfect, but if I were to do it again I'd probably add some LEDs, just out of curiosity.

thats basically the amount of space im working with so this should be a good run.