# C02 dosing question



## pyrrolin (Jan 11, 2012)

I just set up a DIY C02 sytem. The amount im doing is for about 20 to 30 gallon tank but doing it on a 90 gallon tank.

My question is, does the tank size matter or the amount of plants? Right now the plants are fairly small and the tank is far from being fully planted.

So, do you dose for the amount of plants or just the tank size?

It will be a while before I get test kits to be able to push for the optimal amount of C02 and I want to know if my current setup might already be too much.


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## Zebrapl3co (Mar 29, 2006)

I guess the correct answer would be both. It's actually extremely wastefull to run a big tank with very few plants, but I don't think there is a lot of other choices if you are just starting out. My own preference would have been to spend a bit more money to get a decent amount of plants or to grow out a bunch from a smaller tank. Then transfer them to the bigger tank when you're got enough to go on.
Why? Well, with the increase in volume of water, you'll need to up the CO2 dosage to make enough of it available in the water column for the plants to use. You go cheap and your plants will simply grow less. But this present a problem because 1/2 of the CO2 will dissipate into the air as a result of the bigger surface area. Even with fertz, you'll need more fertz but dose less frequent and also, if you are trying to maximize your plants growth rate, it's hard as you'll know that algae will benifit the most in these kinds of setup. That's why you need to plant them in decent size to start with. It'll help minimize the condition for algea to set in and take over the tank.

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## baozi2089 (May 17, 2009)

The key is to get your CO2 to a certain "concentration".
The tank size determines how much you need to inject to reach that level. The bigger the tank, the CO2 will get diluted more and the more you will need to hit that optimal level.
The plant mass determines how fast CO2 will be be depleted from your tank. The more you have the more CO2 you'll need to supply to keep your CO2 at a steady level.

Getting the exact balance is very difficult, because your plants will be continuously growing. Some people keep CO2 always in excess to account for this, but for a big tank without the right CO2 system it can be difficult to manage. I use a pH meter coupled with pressurized CO2, it does the balancing for me so I don't need to worry abt algae associated with not enough CO2 or too much CO2 gassing my livestock. The timer turns it off at night, doubling the life span of the CO2 tank. Check on kijiji or sth, you can probably find a good deal on the set up. It's something worth considering if you want to go high tech but minimal maintenance. 
Cheers bro.


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## DaFishMan (Dec 19, 2006)

No matter what tank size most people aim for 30 ppm of Co2. In my 75g i aim for 15ppm. Most of my plants are the easier type, I'm merely boosting the plants health and growth. some. Even that much makes quite a difference and keeps the Ph at 6.8 for the south-American fish and plants.


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