CO2 for Aquarium Plants?

Has anybody connected their fermentation lock to their fish tank? I grow plants in my aquarium and would like to introduce CO2 to promote growth. Pressurized CO2 systems cost money, and primary fermentors make CO2. Just thinking out loud here...

I was into planted tanks years ago and used CO2 bottles, but reading on message boards like this I saw some aquarists used to ferment sugar water in 2L bottles and pipe the CO2 into their aquariums. thing is they had to keep tabs on when CO2 production was slowing and get another batch going. I imagine it would be similar.

FWIW, I'm using the same regulators and CO2 equipment for kegging and force carbing that I used on my planted and reef aquariums.

Seems like the co2 output from a batch of beer might be very high for a very brief period of time, and therefore not very helpful. You don't want to gas your fish, or have the co2 levels fluctuate so much.

However, you certainly can add co2 to an aquarium by fermentation. Google diy co2, or search threads on a forum like Plantedtank.net.

Before I went pressurized, I used diy co2 on my 29 gallon and my 20 gallon, and it worked quite well. I still use diy co2 on my 2.5 gallon nano tanks.

I did the DIY co2 as well. Sugar water in a bubba keg piped and defused in. You can use co2 out of a tank the biggest thing is the injection into the water. Bubble counter is the easiest to keep track. Just remember when you turn off your lights the plants will stop taking the co2 in. So you can gas your fish at night. Proper co2 balance or turning the co2 off at night will prevent this.