Should I stay with 2 400w HPS or..

Switch to 2 315w CMH?

I have basically a 4x3x7 area and have 2 400w HPS but was thinking about putting in2 315w CMH instead..

Any thoughts?

I was pulling a 1/4lb per plant (2 plants under 1 400w HPS) and now have 2 400w HPS.. I like the efficiency and heat bonuses but really don’t have issues with either.

I would honestly move to 1 x 600w HPS in a air-cooled reflector. You will use less wattage and I think you will see noticeable gains.

The difference from 400w to 600w is very noticeable, your buds will get much denser and larger, and the internodal spacing will decrease (more buds per plant). Don't mess with CMH, HPS is noticeably better for bloom.

You could also go with a 600w even a 900w bloom configured LED. In my grow op, I actually use both HPS and LED combined since I still see LED's lacking in penetration (lower buds suffer).

In veg, use whatever you want I would recommend high temp light like 6500k CFLs or T5's or White & Blue 3w/5w Cree chips (LEDS).

Edit: CMH is overstated and over-rated. Ive yet to see any serious growers up in the Emerald Triangle here move from their Hortilux 600/1000w HPS to CMH. Everyone seems to be moving instead to LEDs or mixing LEDs with HPS.

I agree with theinhibitor id recomend just going with 1 600w and how do you like the led hps thein i use hps was thinking of grabbing some led supplement.

prpgdad said:

I agree with theinhibitor id recomend just going with 1 600w and how do you like the led hps thein i use hps was thinking of grabbing some led supplement.

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Love it. Plants love it too. When I first added a 600w LED to my 600W HPS, the band in between the two had the most intense growth ive seen w/o using a CO2 generator. Only problem that occurs is that the leds usually need to be close to the leaves so i usually tilt the led and move it to edge of the grow tent/area so it shines 20-30 degrees into the center of the grow and sits lower.

Id also recommend getting only 5w/6w chips for bloom (They should say, or you can divide total wattage by # of LEDs to get watt per chip - higher chip watt is better quality and usually more expensive). 3w are OK too, but need to be even closer to the leaves.

I now use white LED's solely for my veg, no more CFLs or T5s. Just one 180w white LED panel with 3w chips can cover a 4ft x 4ft veg area which is amazing.

He's got 2 400 watters, so 800 watts. In my opinion I would stick with those first and grow a couple rounds with both of them. See how you like them before you drop the dough on the cmh's unless money is no issue.