# How much CO2?



## mauve (Apr 12, 2010)

Hi,
I am wondering how much CO2 is enough and not too much.
So far I been bubbling right into the intake of my filter. When it slows down i just put a new batch of yeast and sugar... The results have been astonishing. My plants grew 2-4 times the size they were before just in 3 weeks! New leaves on dwarf saggitaria are 3 times the length, and the sword whose leaves were no more than 3", grew two 10" ones in a week.

Now I find that people actually count bubbles, what's that all about?


----------



## Darkblade48 (Jan 28, 2008)

Counting bubbles is more relevant when you are using pressurized CO2, but can also be applied to yeast. It serves as an initial starting point, so that you can roughly gauge how much CO2 you are pumping into your aquarium. For example, you may read that people use x BPS (bubbles per second) for a y sized aquarium.

However, BPS is a very rough estimate, as bubble size, diffusion efficiency, etc., can vary from aquarium to aquarium.

The best method to determine your CO2 levels is to use a drop checker with a 4 dkH reference solution.


----------



## mauve (Apr 12, 2010)

Right.
Any other experiences and opinions?


----------



## Mr Fishies (Sep 21, 2007)

Bubble counts, as DB said are a rough means of estimating flow. 

I know when I have my CO2 bubbling at 3-3.5 bps I get ~30ppm CO2 in my tank - according to my drop checker. If my bubble counter wasn't made with 1/8 airline as a nozzle, say instead had a 1/16 or smaller orifice, 3bps would be totally different.

When I change my CO2 cylinder, everything is shut off, disassembled and when I hook things back up and need to get back to normal, bps is a quick way to get back close to where it was before. The drop checker is the best reference but takes a long time (30+ minutes) to change so it's not practical to quickly reestablish CO2 injection levels.

Once things are up and running - the drop checker and/or fish behavior are my guides.


----------



## mauve (Apr 12, 2010)

So you can tell by fish behavior if the CO2 is too much?


----------



## Mr Fishies (Sep 21, 2007)

If your drop checker is yellow and/or your fish are hanging out by the surface of the tank, gasping for air...

I don't recommend using fish as a means of setting my CO2 levels - it's just that too much CO2, although not the same as not enough oxygen, results in asphyxia. So fish do what fish do when they can't breathe.

If you're injecting CO2 and your drop checker is not yellow, maybe not even green, if your fish are ever gasping at the surface, trust the fish, not the drop checker (or bubble count).


----------



## BettaBeats (Jan 14, 2010)

Take your pH reading and compare it to your KH reading. It's rough, but it gives you an OK estimate.

I believe the fish would gulp air at the surface if it's too much CO2 - *but they might not!*

A good chart is on this site:
http://www.petfish.net/articles/Aquatic_Plants/Mea_CO2.php

However, I have stiphodon gobies that need highly oxygenated water. One of my calculations had a CO2 level of 45 - outside the 'good' range, but the gobies didn't respond differently.

Plus, check your CO2 levels in the morning, halfway through your day, and in the evening. Then you can see how much of a swing your pH has. 
You might even want to increase you KH with calcium carbonate (baking soda) if the swing is too much.


----------

