How much CO2 in a planted 80 gal?

[BradleyTCO]

I looked into buying one of the Hagen Natural CO2 systems which suggested using 3 units for a 75 gallon aquarium. I have an 80 gallon and have decided to instead use a DIY 2-liter soda bottle CO2 setup. Will only one soda bottle be enough output for a typical planted 80 gallon, or will I need to use two or even three soda bottles?

 

[justDIY]

in my opinion, the yeast method of generating co2 will be insufficent for a tank that size, due mostly to the surface area of the water being able to off-gas so quickly

if you use a tight fitting glass cover that has minimal "air holes", then co2 should build up to a usuable level. if you really want to try doing it yourself, I recommend a visit to walmart or sams club and buy the big 25lb bag of sugar and the 1lb brick of yeast - you'll be needing it, since you'll want at least 6 soda bottles, and recharge two bottles every week to keep the co2 pumping.

 

[Guest]

With that size tank and the quantity of sugar you will use, it won't take more than a few months before you will have spent just as much money buying sugar as you would have to purchase a high pressure co2 system. Also, changing the diy co2 all the time quickly becomes a big PITA. Seriously consider going with high pressure.

 

[Guest]

If you really want to attempt DIY on a 80 gallon tank then you should run at a minimum of 6 liters of mix, 8 would be better. For safety use juice bottles instead of soda bottles as they are much less likely to fall over.

The big question is how are you going to diffuse the CO2 into the water? And IMHO you would be better off with a basic pressurized system,