4x4 and 315w CMH... how much is too much?

DBaldass · Jan 20, 2020

I currently have a 4 x 4 room set up. I have one 315 W CMH and another 315 W CMH it has a dimmable switch but I’m wondering how much light is too much light? Height is not a problem as I can go to the ceiling with the light but I am trying to avoid problems before hand. I appreciate any input.

Matthewstever · Jan 20, 2020

Biggest issue I see would be heat...but the plants will tell you when enough is enough...if there's too much light, they will start to bleach from the top down...even if the heat is ok...
I think the limit for most plants is around 85k lux...here in the desert we get 120k lux in the summer and I have to share the outdoor plants

BigCube · Jan 20, 2020

I've had a 315cmh in a 3x3 and it was a bit much. I can see 2 in a 4x4 being too much. But seeing as you can go 8ft up, it might actually work nice.

The fact that one of them is dimmable would make my try it. If you can handle the heat dissipation, it should be do-able.

DBaldass · Jan 20, 2020

Thanks for the input people! All input is welcome!! Knowledge is power and I’m looking to get stronger!

Matthewstever · Jan 20, 2020

Matthewstever said:
Biggest issue I see would be heat...but the plants will tell you when enough is enough...if there's too much light, they will start to bleach from the top down...even if the heat is ok...
I think the limit for most plants is around 85k lux...here in the desert we get 120k lux in the summer and I have to share the outdoor plants

Shade, not share.

MIMedGrower · Jan 20, 2020

630 watts of cmh is almost equal to 1000 watt se hps. Can be done in a 4x4 but would be a super high intensity grow and the plants could use added co2 to keep up.

DBaldass · Jan 20, 2020

MIMedGrower said:
630 watts of cmh is almost equal to 1000 watt se hps. Can be done in a 4x4 but would be a super high intensity grow and the plants could use added co2 to keep up.

Sas

MIMedGrower said:
630 watts of cmh is almost equal to 1000 watt se hps. Can be done in a 4x4 but would be a super high intensity grow and the plants could use added co2 to keep up.

when do I add the CO2?

MIMedGrower · Jan 20, 2020

DBaldass said:
Sas

when do I add the CO2?

I have not used it. I run a ventilated room. But most growers use it from early veg until peak flower.

Need a sealed room to use it effectively.

Bmg1982 · Jan 20, 2020

Really depends on temps, off the top of my head, at °85 your plants will uptake about 1000-1200 ppm co2, and won't utilize it when lights are out.

I aim to keep my tents around 78-80f. Depending on your substrate, you can feed your microbes a ton of carbs and they will easily shit out 800 ppm in co2. I use Sucanat with great results.

Best applied from veg through stretch whatever method ends up working best for your environment.

Ryboburton · Mar 5, 2020

I’m using a 315 cmh also in an all reflective as construction. I ran out of room and want a veg space as well as flower so I’m going to veg in an empty closet. Maybe led there because of heat but haven’t got there yet. First grow. Have good help tho. Anyway my question is are two 315’s too much in flower? I already have one and money isn’t the issue but if I can get another one and flower under them it would be nice. I can handle any heat and or humidity issues. Currently at 74 degrees and 54 rh with vents going. Do ductwork for a living. I want the light for flower but can go with a 600 cmh just as easily Plant is humbodlt sour d and it was overwatered in cups :(. Hence the yellow leaves but been corrected and healthy now