So here’s a simple way I came up with to allow this dry ice to last several days and provide a somewhat consistent co2 boost to your garden.

Dry ice is essentially just frozen co2 which will sublimate or “dissolve” directly from a solid to a gas, which is the co2 our plants need! The issue with just buying (or making) dry ice and putting it into your grow space is that the dry ice will melt or “gas off” too quickly, causing toxic levels of co2 in your grow, as well as wasting your dry ice! The trick is you need to regulate how quickly it gasses off, and it’s so simple you can do it with items you already have available.

I first came up with this when I did a dry ice ethanol extraction run of some flower to create a concentrate for vape carts. When I was finished, I had a lot of dry ice leftover, and the co2 levels in my lung room were sky high, so I knew I could figure out a way to utilize this dry ice to increase my co2 levels in my grow, and save a few days worth of bottled co2.

Throughout my researching of the best practices for dry ice ethanol extraction, I found something mentioned frequently, which was to ensure you don’t put dry ice into a sealed container, as it’ll increase in pressure as the dry ice off-gasses leading to an explosion. Suggestions to keep your dry ice lasting longer also include putting up crumpled up paper in the container to reduce air space, and a cooler to keep the temperature lower.

I grow in a conditioned Lung Room that’s about 10’x15’ with 8’ ceilings. Over the course of 4 days, with no supplementation other than the dry ice, the level maintained in the mid-700’s before vanishing. The ambient is around 400 in the room if lights are on and no co2 is flowing, so this was a nice bump to see.

At the time of this experiment, I wasn’t utilizing any sort of co2 controller outside of an intermittent timer, which I set based on the readings of the co2 meter. So I just shut my tank off during these few days. I now have a AC Infinity CO2 controller, so next time I have spare dry ice, it’ll maintain around 1000, only turning on to supplement, vs my previous system which would turn on no matter what, sometimes spiking the levels above 1800. Just a waste of co2 more than anything.