I was just browsing through this site's FAQs and I noticed that it says you should keep the temp at 80-90. I'm on my second run with CO2 and I've been going broke trying to keep the temp at 75. The person who sold me my regulator said that the plants can take a higher temp with CO2 but still thrive at 75-78 and yeild better. Now I'm reading the opposite here. I'd love to turn off my ac but it makes me nervous. I'm 4 weeks into flower and everything looks happy.
I would very much appreciate any advice on the subject. Has anyone tried this before? If so, what temp and CO2 levels did you try to maintain and what were the results? Does higher temp allow more nutrient intake as well? I'm already giving them a lot of nutes, about 1300ppm not including sweet and karma. Thanks

You can easily hit 90 with co2 and it does fine. You can run hotter with co2 than without. You got a ppm meter for the co2? Should keep it about the same as your nute ppm and only on when lights are on.

Thanks man. I actually don't have a CO2 meter. I was hoping to get one for the next run. The regulator I have is set on a slow leak when the lights are on. I'm shooting for 1500ppm but I don't actually know for sure. I think my ac is wasting some. I'll buy one of those one time use testers before I raise the temp. I guess my main question is; which will yeild better? Right now they appear to be on pace for a very nice yeild. That is why I am very reluctant to change anything. But when I read the FAQ I got the impression that the heat would actually increase the yeild. What do you think? Have you tried it both ways? I just moved and set up a new room and I'm way overbudget. I can't afford to screw this one up. What should I do? Thanks again for the help.

Hi btownbudda,

As killerweed420 pointed out co2 allows you to be able to run higher temps but it is not necessary to run higher temps to see the benifits of it. Plus while 1500 ppm is nice level for higher temps like 90 or so, at 75-80 you get the same increase in growth rate with a lower amount, maybe 800-1000 ppm.

Here's a source for a couple of CO2 meters, the least expensive I've seen. I have and use the TIM-8 in my personal grow. And the PC-board one to interface to a computer holds much promise in setting up your own control system. CO2 Meter | Indoor Air Quality Products - Welcome Just saw the one on sale for $129.95, does alot for the money!

Thanks oldmac,
Those meters are much cheaper than the one I was looking at. The advantage to the other one is that it hooks up to my regulator and maintains the desired level. Sounds like I could probably slow down my leak for now. Still, it would probably be more cost effective to lose the AC instead. Assuming, of course, that the yeild would not be effected. I just want to do what's optimal. I understand that they can take more heat with CO2. My question is; which is better? Does more heat speed up photosynthesis and the grow rate? Or do the plants still thrive and yeild the best at 75-80? What temp/CO2 ppm/nute ppm do you use for late flowering?

There was a scientific study done on exactly this. It is very informative on light , co2, and temps.
Here is a thread about it...
http://www.springerlink.com/content/...3/fulltext.pdf
It is a scientific document, so basically, what it says is optimum temps are 77-86f for water uptake, even at different co2 levels. This is a study done on cannabis sativa, do not know if indica would be different.

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That link doesn't seem to be working for me

Try this and see what happens:

synthesis of cadralazine springer king at springerkink.com

I have it saved, and should be able to shortcut it but I suck with a computer, so I typed out the entire address.

I think McDanger is sleeping around other boards.
BTW thanks for posting it McD.

Sorry, screwed it up somehow.

Let me try and move it in my computer to another file and see if I can post it correctly later.

Well lets see if this works, I tried to post it as an attachment but the file is too big, so we try this link again with a twist.

http://springerlink.com/content/a352...3/fulltext.pdf

I think I got it this time. I'm really more comfortable with a yellow legal pad and a #2 Ticonderoga.

It's a winner.

NICE!!! That's exactly what I was looking for. Thanks guys. I think I'm gonna have to read through it later when I'm a little less blazed. It seems pretty dense. Still if anyone has any personal experience they'd like to share it would be much appreciated.