The how to and why fors of CO2 supplementation for growers

[Dr. Conjuror]

Thanks sparkjumper. I was under the impression that levels above 1500ppm just would not bring much additional benefit than being at 1500ppm, ,but that it certainly would not hurt. I am not sure what to think now.

Dr. Conjuror

 

[sparkjumper]

Lazyman plants give off quite a bit of co2 during dark hours,I dont have it on at night so its all being produced by the plants.If my level falls to 1450 it kicks the burner on and it stays on until 1500PPM then kicks off.The co2 level continues to rise a bit though,usually to about 1600-1650PPM then it starts to fall slowly.I used to think it was the pilot light producing all that co2 during dark gours,until I killed the pilot light one night

 

[*mistress*]

good thread.

 

[foaf]

thanks for the thread. Ive had fun playing with co2 in my sealed room and used a special "super fuzzy logic" programming to control the levels. CAP controller used as an input to a RCS programmable automation relay controller. I think Im gonna skip co2 on my next grow just to see how much difference there is. thanks again.

 

[inreplyavalon]

Lazyman much respect for this informative thread.

Just so i am clear.

Generators cannot be used in a 'fuzzy logic' type application? How then are they accurately keeping the CO2 ppm around 1500? I understand that the fuzzy mode specifically prevents the overshooting of CO2, but do the generators, coupled with a controller, have a way of dialing in a specific ppm?

How much stronger of an AC would be needed to keep a 13x13 ft space cool if a generator were added to the space? approximate figure of course!

Thanks folks

 

[Lazyman]

Correct, Fuzzy mode apparently rapid cycles the regulator on a tank setup, but generators don't light and relight that fast so they would get damaged. Regular infrared controllers adjust the PPM, usually you can program in a set range and it will maintain that. It will typically let the PPM drop to 1450, then the burner will kick on and run up to 1550 and turn off.

Stronger AC, well a 10K BTU burner adds 10K btu of heat, but you haven't provided enough info for more detail than that.

 

[sparkjumper]

Yea thats right the burner kicks on 50PPM below setpoint and kicks off 50 PPM above setpoint.Earlier I said my burner kicks back off at 1500 which is my setpoint,so that was wrong

 

[Mr-B]

I have a couple questions:

First, my setup: 4' x 4' x 8' air tight. I'm on the bottle with infrared cap controller set at 1200.
Lighting: Vented cool tube pulling air from under the house exhausting through the roof outside. I have an ac that has yet to be turned on.
I'm setting up a can filter tonight.

1. Does the air in the room need to be exchanged with new, fresh air at all? I have the controller set to open a normally closed vent and exchange the air in the room every 2 hours while the lights are on.
I did this because I read somewhere that the air needs to be replenished with fresh air every so often, is that true?
(This comes from the post questioning the levels of fresh o2 in the room.)

2. I have a vortex 265 placed above the grow room in the attic, I planned on hanging the new can filter from the ceiling of the room and exhausting this outside. My controller will turn the vortex on and exhaust the air every 2 hours or in case the temps get over 85 degrees. Does this sound correct?


This is my first sealed setup and I want to make sure I don't kill off a bunch of new plants scheduled to go 12/12 next week.

Thanks for the help.

B

 

[sparkjumper]

No in a sealed room the air is never replenished there is no need for it.You can hang a can filter right in the room I find it easier to use vaportek products

 

[BerndV]

I have the same question as Mr-B. I have read several sources that state clearly that even in a sealed CO2 enriched room that fresh air ventilation every few hours is necessary.

 

[mikeross]

I have the same question as Mr-B. I have read several sources that state clearly that even in a sealed CO2 enriched room that fresh air ventilation every few hours is necessary.

Post up some of your sources... I honestly have never read anywhere that states air needs to be exchanged every few hours in a sealed room with c02. I have read many many times that its not necessary to vent a sealed room. If you go in your room on a daily bases, you going in and out of the room once a day is more than enough exchange imo... Although not needed.

 

[sparkjumper]

Even if he printed up something from the internet,I'll go with what I've been doing for years.I dont think interrupting a steady high co2 PPM to replenish with air when a steady high PPM of co2 not oxygen is whats important.Really I've never done it and don't know anybody here with a sealed room that does it.If I did I'd ask him why

 

[Lazyman]

No you do not need air exchange with the lights/CO2 on, whatsoever. WHoever said that is either a fool or they have heat problems only an emergency exhaust fan can help (because their AC isn't big enough most likely.)

Venting with lights/CO2 off is ok, many like to do at least 1 purge during night hours to vent the extra oxygen from the room that the plants give off at night, but probably also unneccessary.

 

[BerndV]

Post up some of your sources... I honestly have never read anywhere that states air needs to be exchanged every few hours in a sealed room with c02. I have read many many times that its not necessary to vent a sealed room. If you go in your room on a daily bases, you going in and out of the room once a day is more than enough exchange imo... Although not needed.

A grower on the Green House Seeds forum (dominicangreen) has a killer grow room and describes how he vents every three hours during lights-on and continuously at night. Also, while I realize his advice and books are somewhat questionable, Jorge Cervantes states in his latest book on page 322 that "Carbon dioxide-enriched plants still need ventilation to remove stale, humid air and promote plant health" and on page 326 "The room must also have a vent fan with flaps or a baffle. The vent fan will remove the stale air that will be replaced with CO2-enriched air." However, if there is absolutely no need to ventilate during lights-on other than for cooling, that information would certainly be helpful because it greatly simplifies enrichment timing. I am in the process of converting my 7'x8'x10' grow room to include CO2 with a Sentinel controller and I want to do it correctly.

 

[caljim]

I run a completely sealed room, NO AIR IN OR OUT. At times I have used a carbon scrubber to scrub the air inside the room. Other times I have gone without, didn't seem to make a difference either way.

Many people use co2 hoping to pump up yields, I use it as a way to run higher temps with less demand on the a/c, and a way to avoid the added noise and big filter/fan required to vent the room. If bigger buds are part of the deal, well thats OK too.

 

[Mr-B]

A grower on the Green House Seeds forum (dominicangreen) has a killer grow room and describes how he vents every three hours during lights-on and continuously at night. Also, while I realize his advice and books are somewhat questionable, Jorge Cervantes states in his latest book on page 322 that "Carbon dioxide-enriched plants still need ventilation to remove stale, humid air and promote plant health" and on page 326 "The room must also have a vent fan with flaps or a baffle. The vent fan will remove the stale air that will be replaced with CO2-enriched air." However, if there is absolutely no need to ventilate during lights-on other than for cooling, that information would certainly be helpful because it greatly simplifies enrichment timing. I am in the process of converting my 7'x8'x10' grow room to include CO2 with a Sentinel controller and I want to do it correctly.

Thats where i read it!!!!

The medical marijuana growers bible.

I question has been answered.

 

[Lazyman]

Removing stale humid air is only necessary in a poorly set up sealed room. Sufficient dehumidification and air conditioning are necessary to keep the room sealed tightly. Anything less and you should not be bothering with CO2!

 

[ItsGrowTime]

^^^^
I disagree with your last sentence. Ive been running CO2 now for a few weeks and my room is not sealed. It's not actively exhausted but it's not sealed either. I can keep ppms 1400-1500 the whole lights on period. I go through bottles faster than if my room were completely sealed but I do see the difference CO2 and slightly higher temps makes.

The real question is whether a grower has the extra cash (and ability to be inconspicuous) to replace the bottles or canisters more often.

 

[Lazyman]

I know many folks like to bend the rules, and experienced growers like yourself are allowed, but for novices I'd really rather them learn the correct way to do things first, THEN they can experiment later. How often you're willing to deal with bottle or propane tank swaps is up to you, but here's a good example of why a room should be sealed:

I borrowed a friends 24K BTU Generator and Sentinel CO2 controller for my 8KW grow, and fired it up. It took an hour to get to 1400PPM (couldn't hit 1500, the heat already had the room up to 90*) and then I let it kick off. Five minutes later it had dropped to 1200 PPM, and took ten more minutes to get back to 1400. At that rate, a propane tank would have lasted me for 3 days.

This was due to a leakier-than-expected building to be sure, but burning that much propane at $10-20 a tank is simply unacceptable for most people, and was promptly discontinued.

Put another way, picture your grow filled to the ceiling with fresh vaporized weed, every place it leaks out is costing you more and more money. If you have to replace a bottle every two weeks instead of 3, then that might be ok for you, but not for everyone. If it leaked out in 2 days, would you still use it?

Optimizing grow rooms should start with the ideals, and then make small sacrifices if absolutely necessary.

 

[ItsGrowTime]

That I certainly can agree with. Don't bother with CO2 in any form until all other variables are addressed and every other environmental factor is dialed in. Then there's knowing your strain and proper training, etc.

By default, a novice will have to wait a good long while before experimenting with CO2. It's taken me nearly 3 years to get to this point. But now the extra $100 or so per crop for extra CO2 bottles pales in comparison to the extra results without CO2 supplementation at all.