Excessive Co2 in my flower chamber is killing my plants

I am stumped as to where it is coming from. I have a C02 meter with a digital readout on my greenhouse controller, and it is reading above 1700 continuously. Thing is I am not injecting C02 into the chamber at all. My tent dimensions are 8'x4'x6'. I am running a 6" vortex fan 24 hrs a day, and have taped off all lower air input ports, so that only fresh air is coming in from upper ports of the tent. Because C02 is a gas, it is heavier than air and migrates towards the floor. My thinking was that this would have to lower the C02 concentration inside the tent since the vortex is on the floor sucking out C02, while at the same time bringing in fresh air from near the top of the tent. Yet still the readings on the meter show 1700ppm inside the flowering chamber. Using a 1000w MH and HPS bulbs, I have had several successful grows out of this tent and have never experienced the high C02 concentration before. What really baffles me is that I have a seedling tent setup right next to the flowering tent, and those plants are thriving, no dried up leaves like in the flowering tent. Could the 1000w HPS be causing this? It is constantly air cooled to keep the heat down inside the tent. I do not believe it is a heat problem, I think I would notice excessive heat blasting me when I open the tent up. I'm freaking out, I've never seen or have ever heard of anybody else having this kind of problem. If the "C02 leak" is outside the tent, how come my seedlings are fine where my flowering plants leaves are shriveling up, and 5 plants have dried up and died. I have tried a dehumidifier outside the tents, but this had no effect inside the flowering tent, the C02 was still too high. I wonder what if anything inside the flowering tent could be raising the C02 levels. The potting soil maybe? The magnetic lamp ballast? The HPS reacting with chemicals from the inside lining of the tent, creating C02? What can I use to measure the C02 outside the tent if that is where the C02 is coming from? If the C02 is high outside the tents, how come it is not affecting my seedlings in a nearby tent. I'd assume that 1000w would be too much if this had dried out previous crops, but I have harvested 1.5 lbs each on the last 2 crops. The C02 just should not be this high in anybody's basement. Anyone know how I can neutralize this excess C02?

I'm stumped...bump

You intake should be on the floor your exhaust shoul be by the ceiling. You need fans in the grow space as well to move the stale and fresh air around. Are there asny hot water heaters near the tent or other co2 exhaustung stuff? Very weird situation. An exhaust fan and intake with fans circulating air should control co2 for ur veggies.

There is a water heater nearby, but there is no smell of unburned gas anywhere in the basement. If you stick your nose right on top of water heater controller you can get a tiny whiff of unburned natural gas. I am guessing that the unburned natural gas contains C02. I have suspected the water heater, but where carbon monoxide is odorless, they put something in natural gas so you can smell it if it is leaking from somewhere. And I just can't make out that smell in my basement, my wife doesn't smell anything either. However I guess I can't rule it out as the culprit until I get some leak detection fluid tomorrow.

No, it is the burnt gas that gives off the CO2, not the unburnt + like you said, you would smell it.

Is there any way to measure the CO2 in the surrounding basement air? Outside of the tent?

If it's not the water heater, I have no clue as to where it's coming from, but you need to track down the source.

Is the controller/meter reading properly? It could be something else entirely and you are being misled by a faulty meter.

IDK, I'm stumped. Usually you really have to work to get CO2 levels that high.

Wet

CO2 is ordorless and colorless. >10,000 PPM's and you get a headache. You would know if your levels were that high.