Hey DGC,
To be up front, power consumption and/or big large bud yields are not my concern. I use solar energy and grow only personal bud. What I do care about is tasty terpenes and great medicine. I’m cool with it being super sticky for extract or not for straight smoking fat joints. So resin production is a thought I’m messing around with.
I am using two 315 CMH 3100s in my grow tent. Am I right to assume that if each bulb gives off 1.6 umols/joule and that I am pushing out 3.2 umols/joule total. Which is better than the RSECP 550 LED thats hitting only 2.6 umols/joule. Also somewhere I read that a 315 CMH is equivalent to a 600W HPS. Is this True? Does that potentially mean that I’m pushing the equivalency of a 1200 HPS? If so the 550 is the equivalency of a 1000W HID. I don’t know what any of this means I just want to grow some DANK! Please help me understand what kind of power I am dealing with and how to tame these beast. BTW I’m rocking these in a 3x3x6 grow tent.
Also with all the cool new talk about changing spectrum and/or photo-period time from 12/12 to 18/6 the last week or two of flower positively stressing the plant. What do you think would happen if I put a 315 CMH 3100 WITH a 315 CMH 4100 in the tent the last week or two of flowing? I am able to run both because they do run cooler. (85 degrees for both) My buddy’s RSPEC 550 is dope yet runs a little hotter than just one of my lights. And since I fortunately and accidentally acquired another CMH ballast and and 2 A/C Infinity fans; why not, they rock! Peace and love DGC, I love being a member. The pic is from this grow, my first grow, keepin it real
It’s an efficiency rating. So photons per watt of energy used. Just an example(you get 1.6 photons for every watt used for cmh in comparison to led rspec you’ll get 2.6 photons for each watt used) just made up but the correct idea. So rspec runs about 480 watts so equal to 1248 photons while 315 watt cmh equals 409.5 photons, double that for 630 watts only 819 photons so the rspec is pushing more photons and running at less wattage. The wattage will determine the heat dissipation for the most part and is why his light is running warmer than yours, just using more watts. Using a higher kelvin spectrum later in flower stresses the plant and produces a higher energy wavelength that can simulate trichome production. The 18/6 before harvest is for growth reasons, increase light more yield. Not sure on the cmh vs hps comparison but run about equal efficacy so should be similar output per watt, only thing is hps wastes photons in the ir spectrum which plants can’t use and that increases plant leaf surface temperatures, which might be what your taking about.
hmmmm i seeee. Thank you JustCoolin. So its really about the usable Photons (Photons x Watts) not u/j .
What about the spectrum change from both bulbs being 3100 to one of them being 4200 in the last week of flowering, 12/12 to 18/6? These are things Ive never read anybody doing and want to know if there is any evidence of not ONLY 18/6, or ONLY spectrum change the last week of flower.
But BOTH 18/6 red spectrum cmh 3100 and a blue spectrum cmh 4200 all at the same time for the last week? Thoughts?
That’s basically what micromoles per joule is. Micromoles being the number of photons and joule being watt. That increased blue bulb should be a positive stress on the plant even with the redder bulb in tandem.
thanks JustCoolin
As JustCoolin said, Umols per joule is a measure of efficiency. It basically tells you how many units of light you get for each unit of electricity consumed.
A good comparison is miles per gallon with cars. MPG tells you how many miles a car can go per unit of gas consumed, umols per joule tells you how much light output you get for each unit of electricity consumed.
If you want to compare the TOTAL LIGHT OUTPUT of different lights, you want to look at the “PPF”. This measures how much total light is coming out of a fixture.
HLG 550 (~480w) = 1293 ppf
315w cmh = ~650 ppf
(So the HLG 550 puts out roughly twice the total light as a 315 cmh, while only using about 50% more electricity.)
To keep the car analogy going…
PPF = horsepower
Umols/joule = Miles per gallon
Thanks Soup. Ive read your entire website and bought a Growers Love tee shirt. Support bro thanks. Your thoughts on the 3100 with 4200 cmhs @ 18/6 last week of flower?
I agree efficiency means fuck all. I also don’t like when PPF/D numbers are tossed around in comparative marketing. PPFD is amount of light measured at a certain distance, Like an HPS bulb that puts out 120k lumens at the bulb, but not 6 inches away and certainly not on your plants. Those numbers change depending on distance. A tube, bulb or diode’s wattage and spectral graph are what I look at.
Thanks jmystro. After I looked into it I do agree ppf/d doesn’t mean too much for this specific application.
I looked up diode wattage for 315 cmh and this is the first thing that popped up.
https://guerrillagrowhydroponics.com/led-vs-cmh-lec/
thank you for the direction to look