I’m at a loss for words lol, So I just turned off my co2 a week ago, because I heard you should turn off the last two weeks of flowering because it creates a chemical called ethylene… anyhow my co2 controller has been normally reading around 450-500, just today it was reading in the 1200-1300 range! And I’m not using any co2!? any ideas as to why my co2 level in the room is so high without me using any co2
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Well plants can release CO2. It’s called respiration. At night / lights out.
But, if indoors, the CO2 levels can also spike for a variety of reasons.
Here’s a CO2 sensor normally:
And, when I’m in close quarters breathing heavily at the sensor:
I’d keep an eye on it and if it continues to spike, give us more details on your room and grow environment at the time of the reading. Any appliances nearby such as a water heater, etc.
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Like @Northern_Loki says, your exhaling can definitely increase CO2 levels near your monitor, especially in a tight space with little airflow. But I’m guessing this wasn’t the cause of your spike, right?
By chance, do you have gas heat with the furnace near or above your garden? Or possibly a propane or natural gas fireplace near or above it?
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I just heard this the other day that some thing simple as a pilot light can increase c02 how much? No clue
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My furnace is like. 10ft from my room, I’ve turned the ac on the last couple days!?
Isn’t the normal outdoor levels around the 300-350 ppm mark?
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Grasping for straws here, but you don’t happen to have a large amount of soil in that room do you?
I’m pretty sure plants undergo respiration in the daylight hours as well. 
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Concrete can release co2
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Yeah, if you’re in the US, the temps have been mild and I didn’t think you would have cranked the heat. However, as @Tinytuttle mentioned, even the pilot light can make a difference. It all depends on how your furnace exhaust manages the CO2 byproduct of the gas burning, whether it’s the pilot light or the heat cycle. And, of course, how the air flows in your basement area (judging by the cinder block, I’m assuming you’re set up in the basement) makes a difference.
If your furnace doesn’t have a pilot light, you can rule it out. If it does and you want to confirm if it’s the source, turn off the pilot light for a few hours and see what happens. EDIT: if you do this, turn off the gas, don’t just blow out the light 
Oh, let’s not forget your oven/stove. If it’s gas and it sits above your grow, CO2 is heavier than air, so it will fall to lowest level it can reach. Has anyone been cooking near the time that you noticed the CO2 spike?
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I might…
Double check for micro leaks at any tank/regulator connection.
Take the sensor outside to check readings.
Here I learned to vent my space, espec during lights out - co2 supplemented or not.
https://medteknutrients.com.au/co2-enriched-hydroponic-growing/
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Have you been sheltering at home, or quarantined?
More Co2 than normal maybe.
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How’s the CO2 been behaving today?
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Anyone else live in a condo/apartment/small area. I just got an aranet4 to see what the co2 levels are inside my home and grow area and weather or not co2 supplementation is needed. Wow to my surprise the co2 levels inside are really high. Like 1500-2200ppm. It is at a constant 1500 while my wife and I are home and when we cook dinner(gas range and oven) the ppm spikes to 2000+. Anyone else measure their co2 concentration in a small living space? We do not have any pilot light/water heater/ furnace, only the gas range and oven. The rest of the appliances run on electricity.
This is a screen shot when I woke up this morning.
Yeah its not uncommon, put a sensor in any persons bedroom with the doors n windows closed and the co2 will spike
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That seems pretty excessive though. I mean it’s not a small space. 1400sqft. And the windows and doors are all 50+yrs old so they do not seal very well like a new window or door.
Also that sensor is as far from us sleeping as possible
On the plus side , at least I don’t need to supplement co2. Haha
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A quick google says
a human produces about 2.3lb of co2 in a day.
Another source says a human produces 250ml/quarter of a litre of co2 every minute.
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Is that the CO2 levels in your apartment, or in your tent? If you tent, are you a living soil grower? If it’s that high in your apartment, are you using propane heat? That would be pretty high just for an apartment.
Edit: Shit… old topic.
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Yeah that’s the level inside the apartment. Not the tent, rockwool anyways. No heat, it doesn’t usually get under 90 out here in sfl. Ac runs all the time all year!
That’s right now 1427
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That seems pretty high. Nothing close to dangerous though.
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