Montanan
Member
Thank you.
315 cmh vs led
- Thread starter beercan
- Start date
Depends on where you live. Where I'm at my grow room would get to 60 without heating when using LEDs and it was perfect with HPS without heating. So now I have to heat my room to 70 and the tents get to where I'm happy lights on and 70 lights off. I used to be able to cut my heating costs but almost a third with HPS to be honest.
cobshopgrow
Well-Known Member
CMH for sure have their deserved place and everybody should feel free to use them and simply grow some good weed.
but hey, you really get more G per watt from leds, even on smaller fixtures.
done with 166W wall watt on average, DIY LED fixture made from relative cheap parts.
its a 3x3 tent , perfect size for a 315CMH (340W wall draw),i have no final numbers yet (need to harvest first) but i bet the yield will be good, nugs are dense.
could not imagine how i would had growen this with a 400W HPS or a 315W CMH in there, the tops are 5 inch from the led strips.
saving about 50 bucks each run in electricity compared to a 400W HPS.
55 kwh jan., 54 kwh feb., 3 kwh march. 3000k 80cri.
5 kwh jan, 5 kwh feb., 0.3 march. 660nm red.
122kwh / 63 days, 1.95khw a day /12h = 163W average... forgot, 2kwh in total for the UVA leds, 2.6W more on average, 166W.
i like my build, the light is well spread etc. but they all cook with the same water, some use more watts some less for the goal, somes spectrum is nicer, more hanging height needed etc.
but a recent generic fixture with 240W should do similar according to their ppfd maps and nonames arent much more money then a noname 315CMH with a philips bulb,
for a propper HLG its really 400$ you need to spend for, while they offer also a cheaper and not so hard to go DIY route, see the 96ers.
its at least a option to consider and these fixtures getting cheaper and better quickly.
my only problem is this 1:1 LED/CMH comparsion of watts as its simply not true.
btw. had some shity temps for a longer time, lower 70s, but this solved itself when i fired up the second tent and the dehumidifier.
atm all perfect, while i had days where i wished myself some more radiant heat.
edit: killed some typos
Last edited:
Brettman
Well-Known Member
@cobshopgrow So 18w per sq foot?
Norml56
Well-Known Member
I do run HLG LED's I have a 5x10 space that has 4 individual qb 288's on a 320watt driver - a 315cmh then 4 more qb 288's on a 320 watt driver.
Look, let me clarify everything I've said in this thread so far, and why I'm saying it.
First and most important, I'm not on any `side`... I'm not trying to knock down CMH or HPS... Everything I'm saying is off the back of the results I'm getting with LED.
I've never hit near 1.5gpw in my life, and now I'm doing it.
The gram per watt was easy, and when I say easy, I mean I took some plants which would have been used for clones then chopped down, and decided to flower them. A gram per watt in those circumstances is not normal. With LED it seems it is.
And when I said in my post above with NO reflective walls, I'm emphasising that this isn't what you'd call a perfect environment for the maximisation of light efficiency.... and I still did that number.
For a CMH or any other high intensity bulb to work well you usually rely on reflectivity or light crossover. That's not the case with LED fixture of these dimensions.
I'm selling you LED because this thread is titled cmh vs led... and in my own experience there's only one winner and it's not even a close race. I hope that comes across in my posts because tone isn't transmittable.
If you dial these in, you'll be grateful to anyone whose opinion swings you towards doing it.
If you or anyone else decides to go with strip fixtures and tunes them in, you'll be glad you did, it's as simple as that. You won't look back.
About my fixtures. They're Bridgelux Eb Gen 3 strips, 3000k, stick onto some 3mm aluminium U Channel and run off a 320 meanwell driver. They're about 4ft long and about 2.5ft wide.
Putting them together is very straight forward and you'll have one to one coaching on this site if you need it. The internet is life changing in that respect.. use it is my advice.
As far as the medium, nothing special... I use Atami bagged coco because it comes pre fertilised and mitigates any buffering issues you might have with something inert like canna, and I mix that about 2:1 with coir chips which I get in a bale and hydrate with a balanced feed.
The environment is kept warm and the roots are kept warm. I have underfloor heating mats - not horticultural heating pads, they're shit and a rip off - which I have hooked up to an inkbird thermostat and I stick the temp probe under the pots and set it for about 26c/79f, that keeps the middle of the rootball a nice toasty 21c/70f even in winter, and I intake from indoors in the bedroom below.
I lower the extraction and raise the air temps with a heater while they're being established. Go warmer than you think you need to and keep it there. Don't worry about your leccy bills, once they're established they seem to do really well on just underfloor heating...
I think the initial heat and humidity helps them to adjust to and process the light, and when you go back to more normal conditions they handle it well. Think of it as a hardening off process if you will, only the other way around... instead of getting them used to the cold, you're giving them extra heat all round.
Once you see that nice lush growth you're after, and you know what you did to get it there, congratulations, you now know how to use LED lights, and you'll never consider anything else until something better comes along.
IMO of course
cobshopgrow
Well-Known Member
on average yes, i go lower beginning of flower and end of flower.
there are phases where they get 20 or 22w a square feet, but also phases they get below 18w a square feet.
22w is troublesome for me in there, consider that i have the whole ceiling taped with leds and theyre quite near to the tops.
GrownAtHighAltitude
Well-Known Member
Got a link to your underfloor heaters? I'm assuming you're not talking about radiant floor but rather the type that is electric and designed to go underneath tile and such. Do you use it on bare floor and underneath a mat of some sort?
Have a look at this. Fit it to your space. If you use insulation boards or not depends on how cold your floor is, using it is more efficient and it's only cheap. You only need 6mm. Heating on top of that.
loose wire heating
Roll out matting
loose wire heating
Roll out matting
Sick job Cob.
Montanan
Member
Your reply was stellar, its not taking much to tip me to the leds. Now I need to look up those parts and get a picture of the build in my mind. The building part is right up my alley. Its the decision part thats been kicking my ass. Its going to take me a day to get back to you with what are likely more than a few follow up questions as I'm trying to clear a grow space today. You really stepped up, Thanks Duke.
I'm lookin at parts page while I'm getting my coffee going. Shit.. I already have a question. Do you have a company you liked ordering parts from? Mix color temps or just straight 3k. How are you getting reds, or are you? Are you augmenting with any other lights. OK... now coffee and cleaning. L8R
It was.
I did.
You're welcome
Future Electronics. It's bulletproof for delivery, the packaging is the best I've ever seen and their delivery is rapid. Can't fault them.
As for the rest of your post, you're over thinking it. Badly.
Forget every other question you've got and get yourself 3000k Bridgelux strips, source your aluminium, and buy your driver from Digikey, another company whose delivery is stupid quick and efficient. Buy a set of Dormer drill bits and This type and This type of wire strippers and These cutters.
Build your light, use it, learn it, then use that as your reference for everything else you buy.
Any difference in all the other aspects you're talking about is minimal and incremental compared to switching to LED in the first place and is massively outweighed by the time you spend fucking around with questions that the horticultural industry still hasn't answered conclusively.
Do side by sides in the future and decide for yourself, you'll probably find you have a hard time gauging any differences to be honest. The only real difference maker is the main spectrum of the light imo. Don't go for a veg light, and don't go higher than 3000k, there's no need. If you want to go lower to a 2700K you can but I can't advise you there because I haven't used it, I don't see what the problem would be and it may be a more effective flower light but I haven't used it so can't give you personal experience.
The 3K does your plants beautifully. That's all I know. It's all you need to know. Get your tools and get your thread on.
Montanan
Member
Montanan
Member
You might want to see someone about your inability to commit to an idea.. AR R R
I am drinking the coolaid Duke...
Psyphish
Well-Known Member
Trichomes don't really say anything about potency or cannabinoid content. Just because something is frosty, doesn't mean it's good weed. These days if a plant isn't absolutely caked, I'd be disappointed no matter what light source.
PJ Diaz
Well-Known Member
I guess you didn't read what I was responding too? It was a question specifically of tricombs. If you want to shift gears to potency or terps, then those are separate but parallel topics.
Norml56
Well-Known Member
Bag appeal! tis important.
Please point me to a very potent plant without trichomes or stfu.
Norml56
Well-Known Member
Yeah! or just shut fuck up! plants need trichomes to be potent everyone knows that!