Thanks Cactus!

I ran across this vendor when I was researching the lamps I use now. Also why I say PAR ain't what it used to be - once you start putting some of this together with more recent information about UV benefits that the standard PAR model gleefully lops off the 'usable' spectrum. The lamps I use have a very high mol output with almost no heat at the light emission surface ( LEDs are covered by a semi-opaque phosphor panel ). When I add CO2, it gets quite interesting. Plenty of light, a dehumidifier to control the resulting transpiration levels and the girls go to town. I've read here and there folks complain about a CO2 stretch issue, I've come to think that is probably due to light spectrum used. I have not seen it with Indicas. Sativas stretch (because they are tall girls by nature) but I've not grown them indoors enough to know them very well.

So, that graph on page 6 graphically describes what has been on my mind for 'bout a year. How to optimize those variables, and then automate the control of the required variables. The rest of the download PDF covers the rest of what I consider the accepted state of the art in artificial environment considerations. But what I didn't expect are specific cannabis recommendations ( that I think would drive many here bananas with disagreement ) that would almost seem correct if I hold my head sideways and stay close to the median of the range they suggest for temperature. I think the most experienced here go more for a fall (end of season) mix for a finish - cooler temperatures ( Color! Terpenes! ) and less humidity to simulate a dry fall to avoid mold and fungus. I was basically driven indoors by damp fall weather (too close to the ocean) that hosed me at finish every year.

So a side effect of changing light sources is canopy temperature. I do not have fans blowing across my canopy. I simply don't need them. When I introduce them - I get powdery mildew. I'm not pounding the canopy with near infrared that then generates radiated heat I need to remove with that sort of air movement. I simply have an exhaust fan to remove the heat ( yes, there is *some* heat generated, the radiating surface on the top runs 130 degrees on the heat sink fins ).

I'm currently thinking of getting CMH lamps for the next run, to compare results.

I'm glad you liked the info. Seems you know your way around spectrum and the science more than the average bear. :)

Very good read @jumpincactus!

I get slightly less stretch with 315 cmh vs 600 hps. Maybe 3" at best. Co2 user as well.

cobz rock :cool:

sixstring said:

cobz rock :cool:

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Indeed they do and they definitely fit the bill of high PPFD lighting!!!

I personally use their plus model and can attest to the power of spectrum. I have talked to Nick the owner and he is a wizard behind it all, dood is a genuine genius and designs with the cultivator in mind. I run 81 degrees at around 45-67%rh. Stays on average around 55. I pump co2 at 1100ppm day and during night at 400ppm. To calm stretch you can actually jump to 700ppm lights off and it will help. I get crazy growth on the lowers, the light hits the plants perfect and they love it. Nick actually recommended 85 lights on and 75 lights off for best growth. The best thing going is that you can call them and speak candidly about your op and they answer questions.

Very nice @Leew421 I appreciate your sharing that. Typically with heavy ppfd and CO2 you can run temps from 85-90 deg F during lights on. What I find interesting was a study out of Purdue U that shows that many of the folks that profess that CO2 needs to be 1500 ppm or higher according to this study is not correct. There is as shown in the study a total saturation point to where it is actually counter productive to run gas at this level as the plant simply cannot utilize these levels and is a waste of gas. Seems the sweet spot is around 900/1000 ppm

I will look in my info vault and see if I can pull up the peer reviewed study for your review.......... :D Peace

1000ppm here and always killer yields. I do not run higher than 80* from flip to week 6. Then I drop temps every week.

jumpincactus said:

Very nice @Leew421 I appreciate your sharing that. Typically with heavy ppfd and CO2 you can run temps from 85-90 deg F during lights on. What I find interesting was a study out of Purdue U that shows that many of the folks that profess that CO2 needs to be 1500 ppm or higher according to this study is not correct. There is as shown in the study a total saturation point to where it is actually counter productive to run gas at this level as the plant simply cannot utilize these levels and is a waste of gas. Seems the sweet spot is around 900/1000 ppm

I will look in my info vault and see if I can pull up the peer reviewed study for your review.......... :D Peace

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For sure, I have come to realize for me 1100 is money. I never hit 1500ppm for one. 1400 maybe on saturation. I found out that anything over 1500ppm is counter productive not to mention costly. Running 1500ppm takes 2.5 days to kill a 20lb bottle. My exhaust filter is right next to my intake filter for veg so I actually keep veg co2 around 700-800. The only time where I have read that super high co2 was useful was some pest. But that's for discussion.

Awesome thread and I think everyone is on the money with their comments.

I'm not convinced leds are there yet as far as ppfd per square foot. I see too many led manufacturers claiming a certain footprint for their fixtures when the edges are not sufficient to grow well. For example the platinum led I bought uses 385 watts and grows killer bud directly under the light. However that footprint is only 1x3.5 at the most. Platinum claims 3x5 footprint for that light. Sure it grows that wide but those outside the 1x3.5 are not quality at all. So I made the switch to cmh. When comparing actual cost, watts, footprints and par the leds just don't match cmh and hps, but I believe someday they will.

StandingRock said:

Awesome thread and I think everyone is on the money with their comments.

I'm not convinced leds are there yet as far as ppfd per square foot. I see too many led manufacturers claiming a certain footprint for their fixtures when the edges are not sufficient to grow well. For example the platinum led I bought uses 385 watts and grows killer bud directly under the light. However that footprint is only 1x3.5 at the most. Platinum claims 3x5 footprint for that light. Sure it grows that wide but those outside the 1x3.5 are not quality at all. So I made the switch to cmh. When comparing actual cost, watts, footprints and par the leds just don't match cmh and hps, but I believe someday they will.

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I had some p600s and didn't like them. The spydr is very true 4x4

Leew421 said:

I had some p600s and didn't like them. The spydr is very true 4x4

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The 600 is what I had too. Not impressed at all. I could have ran a 400 hps and gotten much better results on the entire footprint

The way I see it, the response from co2 at 1500ppm hasn't even leveled off provided you can get photons near the high end of the DLI.


Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions