Dangerous CO2 Level. Need Help

I posted this on another forum but haven't gotten any answer. Situation is getting dangerous since my levels the last 2 days have been 5200 and 4400. I have been growing for about 3 years now and never had CO2 problems except when the scrubbers need replaced. My setup is a 7’ x 13’ sealed grow room in the corner of a 24’x28’ basement that is more like a bunker. The ceiling and walls are concrete with a 36" entry door to the space. No outside air to any of it except opening the door. 2 Days ago, I pulled the CO2 tank completely out of the room to make sure the actual tank wasn't leaking. 2 nights ago, the PPM was 2800 about 1 hour before the lights went out and 5200 in the morning, and last night was 2900, and 4490 this morning. The rest of the 24'x28' space is a woodshop and also has a CO2 monitor. I put it in the grow room and both autopilots I have read the same, so I know that it is not that. This tank is not leaking. I'm pretty sure it's not lockout because the plants still look good, but I don't know what is generating more CO2.

When I built this room, I put in one 3" PVC pipe to the outside in case I ever needed to setup a CO2 Dump but haven't needed it.
Can anyone help with what I should do, or where the excess CO2 could be coming from?

Equipment
Autopilot APC8200 controller/monitor with CO2 tank and regulator that are set to 1300ppm.
Three 6" inline fans with carbon filters, 2 draw from floor and 1 from ceiling. Setup to blow the air in a circle and replaced last week
Mini split
Dehumidifier
2 Spider Farmer SF4000’s and 1 SF2000 for 12 plants on a 4’ x 10’ sliding table.
I grow in FFOF with Advanced Nutrients.
Several circulation Fans

Thanks
David

I don’t use CO2 so probably not much help but have you checked your regulators? I do a lot of welding and have had regulators go bad and they will give you weird readings so you may think your only regulated at 1300ppm but giving far more than that. Just a thought might be worth a check to make sure they are on par. Hope you get it figured out

Treesomewanted77 said:

I don’t use CO2 so probably not much help but have you checked your regulators? I do a lot of welding and have had regulators go bad and they will give you weird readings so you may think your only regulated at 1300ppm but giving far more than that. Just a thought might be worth a check to make sure they are on par. Hope you get it figured out

Click to expand...

Thanks for the reply, I did check it. My son is a pipeline welder and that was the first thing he said. For the last 2 days though, it hasn't even been in the room, I completely unhooked it and took it out. PPM is still rising with no known source in there. I'm running fans pulling air through the main garage, into the woodshop, and then into the grow room to get it to a safe level, but when I close it at night it still rises by 1500-2200 on its own.

cdsmith12 said:

Thanks for the reply, I did check it. My son is a pipeline welder and that was the first thing he said. For the last 2 days though, it hasn't even been in the room, I completely unhooked it and took it out. PPM is still rising with no known source in there. I'm running fans pulling air through the main garage, into the woodshop, and then into the grow room to get it to a safe level, but when I close it at night it still rises by 1500-2200 on its own.

Click to expand...

Copy that didn’t see that part. Is there any appliances with maybe a pilot light near by that would add C02? That’s about all I can think of but being in a sealed room it shouldn’t be rising if it’s not pulling anything from outside the room so that’s a hard one. Hopefully the more experienced with C02 will show up soon and be able to shine some light on it.

So the over night rise in CO2 is normal. The more plant mass you have in there the more you should see the CO2 rise. That being said I only ever see like the CO2 hit like 2-3000 max from 1400ppm in a 12h night. If you have pets or if you spend a lot of time in the room then the CO2 can spike. If I spend 1h+ in the room I can expect the CO2 to rise about 1000ppm sometimes more and of course more if I have a helper or helpers. It is odd you are maintaining a very high level though since my levels drop down to baseline after about 1-2h of lights on.

MidnightSun72 said:

So the over night rise in CO2 is normal. The more plant mass you have in there the more you should see the CO2 rise. That being said I only ever see like the CO2 hit like 2-3000 max from 1400ppm in a 12h night. If you have pets or if you spend a lot of time in the room then the CO2 can spike. If I spend 1h+ in the room I can expect the CO2 to rise about 1000ppm sometimes more and of course more if I have a helper or helpers. It is odd you are maintaining a very high level though since my levels drop down to baseline after about 1-2h of lights on.

Click to expand...

My property has 2 basements, one I turned into the garage, woodshop, and grow room, so there are no outside sources for CO2 besides my wife and I. For 2 1/2 years this never happened. I would leave the grow room, the levels would come down and the CO2 would cycle, but according to the Autopilot, it has not dispensed CO2 for over a month. The numbers I posted on the low end are after I spent an hour or two in there. It will normally be 1500 when I go in, and 2500 when I come out. But for the last month I've been pulling in outside air just to feel safe to go in because of the 4000 plus starting point.

cdsmith12 said:

My property has 2 basements, one I turned into the garage, woodshop, and grow room, so there are no outside sources for CO2 besides my wife and I. For 2 1/2 years this never happened. I would leave the grow room, the levels would come down and the CO2 would cycle, but according to the Autopilot, it has not dispensed CO2 for over a month. The numbers I posted on the low end are after I spent an hour or two in there. It will normally be 1500 when I go in, and 2500 when I come out. But for the last month I've been pulling in outside air just to feel safe to go in because of the 4000 plus starting point.

Click to expand...

Can you take your auto pilot outside and see what it reads? Should be around 390-430ppm outdoors.

That's an alarming mystery. Maybe move the Autopilot around in an attempt to find a source? I'm going to move mine from the living room to the basement out of curiosity, I have a gas water heater.

I did a search, this is the only thing I was unaware of.

Soil Capping

Carbon dioxide occurs naturally in soil as a result of decomposing organic matter. Houses built in the countryside, and particularly on previous farm sites, may be particularly susceptible to elevated carbon dioxide in the soil due to the previous use of fertilizers. This carbon dioxide can be sucked into the house due to the air pressure difference between the soil and the home. An example was highlighted by CO2Meter.com. The site quotes a case where a customer complained that every time it rained, the pilot light in the home furnace went out, and the customer became very ill. A phenomenon called "soil capping" was causing soil to to swell and become waterlogged, leaving no space for soil gases to escape outside. This left the basement, where the furnace was creating negative pressure by pulling air from the basement to the rest of the house as the escape route for the CO2. The pilot went out because excessive CO2 smothered the flame.

1212ham said:

That's an alarming mystery. Maybe move the Autopilot around in an attempt to find a source? I'm going to move mine from the living room to the basement out of curiosity, I have a gas water heater.

I did a search, this is the only thing I was unaware of.

Soil Capping

Carbon dioxide occurs naturally in soil as a result of decomposing organic matter. Houses built in the countryside, and particularly on previous farm sites, may be particularly susceptible to elevated carbon dioxide in the soil due to the previous use of fertilizers. This carbon dioxide can be sucked into the house due to the air pressure difference between the soil and the home. An example was highlighted by CO2Meter.com. The site quotes a case where a customer complained that every time it rained, the pilot light in the home furnace went out, and the customer became very ill. A phenomenon called "soil capping" was causing soil to to swell and become waterlogged, leaving no space for soil gases to escape outside. This left the basement, where the furnace was creating negative pressure by pulling air from the basement to the rest of the house as the escape route for the CO2. The pilot went out because excessive CO2 smothered the flame.

Click to expand...

I read a similar article, and I do live in the middle of a bunch of agricultural fields, ie. beans, corn, milo, etc., but this basement was built in 1973, so I wouldn’t think it would just start happening all these years later. This is on my radar though if I can’t find anything else.

MidnightSun72 said:

Can you take your auto pilot outside and see what it reads? Should be around 390-430ppm outdoors.

Click to expand...

So since I have an Autopilot regular/monitor, and an Autopilot monitor in my wood shop as a precaution, I just took the one from the wood shop outside and it read 448 ppm. Then I took it inside and put it right next to the one in the grow room. The regulator one read 1380, and the monitor from the wood shop read 1395, so they are super close. Those readings are after I had fans blowing outside air in for the last 4 hours. I’m going to get it to this level after my daily watering/trimming and see how high it gets again overnight. Thanks for replying

This could really be a blessing in disguise. Free CO2. If I was in your shoes I would setup extraction fans and set my CO2 controller to start dumping air at 2200ish ppm and stop bringing in new air around 1500ppm.

Absolutely move around the monitor and identify where it goes up and down and find the source. Could be dangerous. Hopefully not!

cdsmith12 said:

Can anyone help with what I should do, or where the excess CO2 could be coming from?

Click to expand...

Perhaps you should be asking yourself where the O2 is going.

One thing is that, by adding CO2, you displace other gases from your room. It just leaves with positive air pressure. O2 is also absorbed by the plant and bacteria for biological processes.

I recommend removing the CO2, especially if you have this all in an enclosed building. Almost nobody has a shortage of CO2 ever. It may also make sense to have a barometer in the room to ensure that negative air pressure is maintained.