Yep. Just a standard candle you'd use on a dinner table. Actually get packs of 5 'emergency' candles at the bargain store for a buck or two and it was one of those.
Just sitting in my flower room the other day for about an hour tending to my girls with no burner going the top LED on the controller was blinking to show it was over 1500 so if you sleep with your plants while their lights are on they are getting lots of extra CO2. It was blinking the bottom light when I first went in.
Unless you have dead static wind conditions it won't sink at all. With my burners the CO2 is rising with the hot air and the 12" oscillating fan that runs 24/7 mixes the whole room from floor to ceiling. A larger 16" fan is bolted to the ceiling aimed to blow across the canopy to create a circular flow in the room. Only a 9x7x6.5' room and I've checked air flow all over the room and even in the corners at the back of the room the air is moving around some.
The only time you can really see CO2 sink is when dry ice sublimes and the 1,000,000ppm CO2 shows as a fog and sinks. If a fan was on it you'd just see a bit at the top of the container it was in. The rest would dissipate into the surrounding air rapidly.
I takes very little CO2 to raise the ppm to optimal levels of around 1500ppm. Other things need to be fine tuned to take advantage of it tho like higher temps, more light and higher nute levels. If any one is less than optimal then the whole chain breaks down.
If I manage to come up with an extra grand I'll get a CO2 tank and a portable A/C unit and run my flower room sealed to keep everything at peak performance. but don't really need to as I'm just growing for my own use so production isn't a huge concern. Getting into breeding CBD strains and have everything I need for decent growing now. After 40 years of growing pot the thrill is gone but it can still be fun.
I love fishing more but if I had to do it to support myself I'd grow to hate it soon enough.