Harvey- Interesting findings, dropping wattages by more then half didn't change your yield. Sweet, I bet you are glad for the savings in the electric bill. Was it noticeably easier to cool with the 250? Did you maintain the same strains while running these tests? (i'm guessin you did)

HMMMM, maybe this will help stem some CFL debates in the future.

To each his own, each person has different needs, but I think this will help save people from buying a 1000 watter when a 600 (or less) will do as well.

I didn't say anything about yield, I haven't changed my flowering wattage. (yet). But what prompted this test, dropping the wattage in my clone/veg setup even more now was I had a 250 over my clones, and a 400 over my veg tubs next the them. As soon as the clones would root, under the 250 they'd almost keep up with the 400. So I said, well, shit, my room's getting too hot, and my veg setup is already overgrowing itself horribly, so might as well drop the wattage and see. So I moved the 250 over the veg tubs and bought a new T5 ho flourescent for the clones. I"ll have to give it a little time, few grows to see how it all really does work.

Before, when I went from 600 to 400 over these same dwc veg tubs though, I did not see a reduction in growth, so the 600 was just too much. That is what Haley's whole question was, is there a saturation point, based on that, I'd say yeah, definitely. Now I'm wondering if I'm at that point with my flowering setup too. I'm going to want to punch myself in the face if I could have been running 400s this whole time in flowering, but live and learn...

as you know Harvey that you don't necessarily need a bunch of light in veg but I'm willing to bet if you go to 400's for flower that you won't want to finish the crop with it in there, just my educated guess. About saturation points and what not, if you got Co2 then it's a totally different ballgame when it comes to saturation point so it's hard not to include Co2 when you're talking about how much light a plant can take. I bet a plant at 1500ppm can take 5x the nutes and easily twice if not three times the amount of light as a plant that is only getting 3-400 ppm and that has been my experience.

Thank you for the lighting clarification Harvey.

I really enjoy trying to learn all of the intricacies of growing this wonderful plant we all love.

I don't have the space for a HID at the moment so I'm happy with what i am working with and learning what works for me.

McLovin- So Co2 helps that much? Sounds like it acts like redbull for em huh? My cabinet is by bedside table, so I'm quite leery of a Co2 overload where I sleep LOL.

Just a quick note SS: CO2 will not harm you, unless it displaces the air in your room. Carbon Monoxide (CO), otoh, can lead to acidosis and death - so no gas fireplaces in my bedrooms!

they do make Carbon Monoxide detectors and yes, it's like legal steroids in a sense. Co2 overload nah, that's the point of a Co2 controller although I'm sure nothing in life is foolproof but that's the chance we take as a jumbo jet could take any of us out on the way to the mailbox but you have to plan ahead and that's all you can do.

This is one of those threads I keep trying to write replies to, and then not posting them. I've already done this 3 times now, written about 3 pages on this shit, only to just keep deleting it/not posting it. I start writing, then start questioning myself, than I just sit there stoned thinking that I have no idea wtf I'm talking about and need to stfu. But I want to figure it out well enough to be able to post about it! Fuck!

Okay, for the 4th try here.. Lol

I think air movement across the leaves, the co2 level in that air, and light try to create a certain level of metabolism in the plants. The nutrients then support that level of metabolism, ideally, also being tailored to the temp and humidity of the environment. (Same for the root o2 level, it is a supporting thing)

McLovin, when you wrote "how much light a plant can take" I'm guessing what you meant was really more like "use"?

Because I know that if I have plants under bright light, if I kill the air movement, they will look good and healthy, but won't grow. They won't burn from not dropping the tds, but they will accomodate a lower tds at that point if I were to drop it.

Then if I pick up the airflow, the growth rate increases. Same thing with co2 for a given airflow level. Pick up the airflow/co2, you increase the plant's ability to grow, provided the nutrients are dialed in, until you hit the limit created by the light.

What I've observed about co2 that makes me want to address that "take more light" thing, is if you don't have your nutrients right for that metabolic rate/growth rate you're suddenly creating with the co2, airflow, and light, raising that metabolism will burn/deprive the shit out of the plants.
Sometimes growing plants too fast reminds me of trying to cut through endless traffic on a CA freeway.
So if you're having problems keeping you plants healthy at ridiculous growth rates, you want to drop that back down a little. At that point, it is a lot better to drop your wattage than your co2, let the wattage be your limiting factor. Co2 costs a lot less than electricity.


Conversely, if you raise your co2 until you hit a plateau, like say you hit a growth rate plateau at 700ppm co2, then you might be able to use more light.

But that's not necessarily that simple either, because I know you can grow at the same rate with the same light with different co2 levels, you just need more airflow across the leaves with lower co2.

Well, that's about I have for now..

When I typed use or take or whatever I used Harvey I meant how much light or PAR can a plant take without getting burned as I have had may plants get burned 10 inches under my Raptor before when those Co2 levels were in the 3-400 range. With Co2 I could let them touch the glass for a couple days with no ill effects and they still kept growing under a 600 watt Solarmax.

You think killing the airflow has a lot to do with the plants not being able to access that Co2 that was once easily blown across like before when the fan was on?


Stale or non moving air isn't the best improvement you can make in a growroom but you know what I mean and totally agree about dropping the light wattage as it's cheaper than Co2. If your system is dialed in and your plants have access to ppm of 1500 or so and everything is looking great, you're doing something right but if something is off at that ppm level then it will easily seek out what's lacking and expose it since the plant is growing faster than it normally would or metabolizes faster I think is the correct term (not real big on the understanding of how a plant works but I sure can grow some lol).


Stop deleting those posts Harvey but in all honesty I do the same thing as sometimes I just start elaborating and going from one thing to the next then I read what the ? was again and realized I answered a bunch of ?'s that weren't asked so I just chunk the whole post usually lol, take it easy buddy

Hey, when you went from 3-400 to 1500, did you go right up to 1500, or do it in stages, watching the plants?

I'm always playing around with my co2, I have a Titan controller and burner I drilled out to run on natural gas. Right now my target is 700ppm, but it goes over that since the burner keeps going until enough co2 cools and sinks down from the ceiling to trigger the controller off. The average is probably 800 or so right now. I've gone from 600 to about 1500. When I was at 1500, it added too much heat to my room, I didn't like it. Dropping down from 13-1400 or so to my current 700 setting, still hasn't made much of a difference in yield/growth. That's what makes me think that the fans blowing across the plants play a huge role in the actual co2 uptake. When I went from an unsealed room with an exhaust fan turned all the way up to sealed, air conditioned, and co2, I did see that typical 30%+ increase in yield, seemingly no matter what I had my co2 set to. Wtf . Lol. But at the higher settings, I saw more plant damage/less healthy looking plants. The leaves just had a more harsh, crispy feel and appearance, same with the buds too, I don't really know how to describe it.

That's why I'm wondering if you went right up to 1500 at once, or experimented, just wondering what you observed also.

Btw, my flowering lights are currently bleaching/burning sections of the top of my canopy, so yeah, I do have too much light, at least with the canopy that high.

I know you're supposed to wean them onto the Co2 but I ran 800-1000 ppm in veg and 1500 ppm in flower but just cranked it on one day and after 2-3 days they were back on track but they did stall for a little bit. I had my Titan controller at the same height as my canopy (perhaps 6 inches higher) on the opposite side of the room as my burner. The longer the burner runs the more it helps with humidity for me so I think the low setting was 14 or 1500 and the high setting was 1800 ppm in flower. I never saw plant damage like you speak of Harvey but I did see the plants look a little funny one day and so I cranked back the Co2 so it wouldn't get worse to fast, forgot what the problem was but think I added to much Liquid Karma as I didn't use a syringe to measure and just poured lol but that was just pure laziness. I'm not a Jorge Cervantes fan at all but I watched a video a long time ago while he was talking about judging a cannabis contest and picked up a bud and could tell from looks and smoking it that it was "pushed too hard" to get the most out of it so I think I understand where you are coming from on that one. I wonder if your canopy would get bleached if your Co2 was higher but understand you don't want to run it that high. Think I was spending about 20 bucks a month on my propane tanks, sometimes shorter in veg, usually a little longer in flower it would last.


If you have no source of fresh air for the plants, Co2 is a must seeing what a difference it makes.