The Real Scoop on Co2

Thanks for the update LF, It snowed here last night! As far as your light intensity question I'm not sure but from my experience it does not. I've got vertical bulbs and the leaves tend to fry if there is no air flow around the plants but the buds stay super sticky (unless you totally fry the plant).

Thanks for the input. I wonder if it is more strain dependent? My last round of Jack herrer got totally heat stressed even though temps were never above 85 running co2? The buds were huge but they got hella "strung out".. when they dried...they looked like shit

This time around it seemed like the plants that are on the fringe look a little more frostier. ?

Hmm, were they heat stressed or light stressed? 85 with C02 sounds extremely ideal to me.
I don't know how useful 1800+ppms would be for a plant because once you pass 1500 ppms there are limiting reagents other than C02 that are not and cannot be met in photosynthesis.
The damaging point for plants however is near 4000 ppms, so you're not really doing any damaging, you could just be wasting money.
Also, I'm not too sure that C02 makes a plant grow faster... rather, it just makes more growth occur in the allotted time period. A 8 week flowering strain will take 8 weeks to flower regardless of climate... at least that's how it's worked for me in the past. Maybe I'm over-ripening my plants, but hey... more cbd for me!

Well they didn't look light stressed to me. No bleaching or anything. Light meter readings were in the 80,000 lux range so that is not super duper extreme or anything. I dunno, they just looked like shit. Yeah, co2 won't make them mature faster but it seems at times that it can actually slow things down a bit. Perhaps its just me. This last run looked great but the JH was fluffy as fuck and they took forever to mature.

My light intensity is extreme with vertical lighting without fans the leaves fry. I think stuff in the CO2 produces more resin, the buds look candy coated as oppossed to really covered with naturally aspirated rooms. Density might also play a factor here too. Heat stress will just screw everything I had a terrible run like that myself.

Well I'm trying to put my finger on why I just don't have that danky dank smell. It could just be the strains I'm running as they were all from medical clones. (thank god I just cloned 5 new strains all from seed that i started). I currently have some endless sky that has big buds bud virtually no smell and chrystals. In the same room and same nute schedule however I have some super lemon haze that is truly wicked looking bud. Its in week 6 of 12 and it looks incredible.

I am running beneficials, have added allot of organic compost type tea and have also been adding a little molasses to the rez as well. You know, now that I think of it, I did use snowstorm as a foliar treatment last run...maybe that is what fuckered things up?

So if you "close" off the room, whats the best type of air conditioner to use? Im just trying to figure out how to get around the whole exhaust thing... i have a portable a/c but i have to vent it out of the room, which would waste all the precious Co2. Help me out guys! how can i solve this problem? I want to have a "closed" environment.

You need to invest in a split unit compressor outside the room with refrigerant lines running to a condenser unit inside. It's also necessary to scrub the room air or exhaust it and replace with fresh at least one a day.

Never heard of exhausting the whole room out once a night. I'm not sure why you would need to do this as you are supplying the co2 to them for growth and there will always be enough oxygen in there for nighttime respiration to occur. 1500PPM is only a .5% concentration of co2. I do run a scrubber however so my house doesn't smell like....well it smells like I'm growing weed in the basement.

The split ac unit is the abosolute best way to go. Not only is there no air exchange and they take up next to no space, they are far and away the most efficient AC unit. The portable units are the least efficient. Right now I just have a window AC mounted in the wall of the flower room and it just exhausts into the basement. Which is fine in the winter as it heats the basement quite nicely but in the summer... lets just say I have been looking at AC units. The cost of a split AC is around $1,000 to $1,500 for the name brand ones.

The great thing about the split units is the condensor mounts outside the house and the coolant lines run to the wall units (which are tiny). The unit I am going to get is going to have dual wall units so one for the grow room and one for my bedroom cause I hate sleeping when its hot out.

The issue i see with a split AC is the fact that you must have it installed (or at very least charged) professionally, as you cannot buy refrigerant unless you are licensed.

They have several models with pre-charged lines.

it seems its worth the hassle of buying co2

NewGrowth said:

I agree with people on the monitoring, if the co2 levels are not near constant the plants don't like it. CAP sells a cheap controller for about $250. It's also nice to have a full climate controller so that you can set fail-safes in case temp or humidity get out of control. If my A/C dies the co2 shuts off and exhaust fans kick on. A properly sealed and enriched room is like a hot rod everything is faster but one small mistake can cause a major crash.
I've not seen any improvement with levels over 1500ppm and it takes VERY high concentrations and time exposure to burn your plants. I run the burner all night sometimes to kill mites. Levels hardly exceed 5000ppm, we saw burn when levels were near 20,000ppm but to even reach that level we had to release a whole tank and run the burner.
If you are not shooting for commercial production I see little need for CO2. Naturally ventilated rooms seem to result in a smaller yield but the buds develop a better aroma and taste. When running a perpetual system it's not a option to cut co2 levels because only a few plants are finishing at a time.
Let me know how cutting down your co2 works LF, putting them outside for a week was night and day for us. If you are able to do that I highly recommend it, something about the outside air and sun does wonders for cannabis.

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i buy into everything you say except the part about high(4000ppm)levels killing bugs.how would this work on insects when most can just hibernate until the climate is favorable again?they say most bugs will live through a nuclear war.did you ever have a bad infestation and actually witness the dead bugs,if so did you keep track of them to see if they came back to life?I'm not trying to start shit,i just want to hear from someone else who does this.i had a friend ask me about it when he got mites and i told him to try it but i was sceptical.i had him keep the room at 4000 ppm at night for 3 nights in a row and first he thought it worked,and about a week after that he wanted to know how many doctor doom cans it would take to fog his roomit seemed to me they were just hibernating and came back full force.

There seems to be differing opions on the level of co2 necessary to kill bugs. Co2 WILL kill all bugs as it is toxic, its not just the fact that oxygen levels are reduced. Grain is stored in super high co2 levels...like 70% co2 which is 700,000 PPM. There are several journal articles out there about co2 concentrations and exposure times to kill various pests. The most usefull article however has units that I can't fucking seem to convert

10,000 ppm is the number I have heard thrown around quite a bit. Some people swear by it. My monitor only reads to 5k. I have gased spider mites before and had mixed success. Again, my rates might not have been high enough. Spider mites and aphids don'[t need a whole lot of co2 to kill them. Fungus knats however need dangerous levels.. Levels that I would not want in my basement...like 100,000 ppm.

in terms of bottled over burner... I HIGHLY recommend you get a burner. A tank only lasts a week at best in a small sealed room and runnning back and fortha nd back and forth to get bottles is a REAL pain in the ass. This is not to mention that bottled co2 is 600% more expensive than propane, or even better NG generated co2. Check out my tankless water heater thread,,,

From what I gather, the room should be sealed for co2 to be effective. However, I am planning a large room with several 1000 hps lights. It's gonna be HOT in there. How can I keep the temperature from spiralling out of control unless I have massive fans/ducts to cool the lights and vent the hot air out?

Bottles are great for small spaces, they produce no heat. Burners are definitely the way to go if you have a room. I've found that Natural Gas releases less humidity into the air VS Propane. I use an IPM (integrated pest management) system to control mites and CO2 is just one of the ways I control mites. The roaches will testify to the fact that co2 can kill, tend to find a lot of dead bugs after a night of enrichment. It's just a way for me to keep the amount of poison sprayed to a minimum.
Here's how my IPM goes:
Veg: alternate spraying of avid and floramite aprox every 30 days all the plants are treated with bannermaxx at this time too.

Flower: depending on mite population plants may get treated the day they are put into flower. After the first week of flower I use CO2 and azadiatrin to keep populations on check.

Recently we had some mites and now we're coming out on the tail end, total eradication takes about 3 weeks with my system.

As far as those pre-charged A/C's I would not recommend them unless you absolutely can not find a cool HVAC guy to set you up. And HVAC company will charge less for the unit and be able to troubleshoot it if there are any problems. Also if you live in a cool climate or plan on running the A/C in outside ambient below 50F, be sure to purchase an "ambient air" unit so you don't fry your compressor and get freezing problems in the winter.

ShadesOfBlue said:

From what I gather, the room should be sealed for co2 to be effective. However, I am planning a large room with several 1000 hps lights. It's gonna be HOT in there. How can I keep the temperature from spiralling out of control unless I have massive fans/ducts to cool the lights and vent the hot air out?

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I think you need to revisit your "plan". If your running several 1000 watt hoods your likely going to need an AC unit with or without AC unless you r grow room is in a cave where the ambient air is a nice consistent 50 degrees. I can attest that if the outside air is above 70, your going to need a fucking jet fan to move enough air to keep you within target temps.

Vented hoods still put off heat, especially 1000 watt hoods.

legallyflying said:

I think you need to revisit your "plan". If your running several 1000 watt hoods your likely going to need an AC unit with or without AC unless you r grow room is in a cave where the ambient air is a nice consistent 50 degrees. I can attest that if the outside air is above 70, your going to need a fucking jet fan to move enough air to keep you within target temps.

Vented hoods still put off heat, especially 1000 watt hoods.

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Okay. I guess I will have to buy an AC unit then. Any recommendations? If I get someone to install a massive AC unit in the room will that keep it "sealed" so that I can still run co2?

I'm sorry but I have literally zero knowledge of heat control - if you can fill me in or direct me to a better resource it would be much appreciated. I. have no idea what I'm talking about.

So I called a few places and they said I need a ductless ac unit. I'm guessing this is what you guys were referring to with the "split unit." The compressor will go on the roof and cables will connect it to the unit within my space. The cost including installation will be around $5,000. Damn. Haha shit ain't cheap.