Signs of too much Co2?

ccLansman

Guru Class Expert
Jan 22, 2008
375
0
16
Vista, Ca
Just trying to get a handle on what to look for or test for in order to see if my co2 is too much. I know we can look for fish gasping at the surface. I have not seen this, but my SAE's seem to be hanging out on the bottom a bit more then they used to. But my tetras and killis are hanging around like normal. Is this our only real indicator of excess or too little co2? Can we also check ph and make any assumptions? My GH outta the tap is about 5 and i put a tsp of gh booster at water change. Does any of this data help me?
 

captain_bu

Prolific Poster
Nov 7, 2007
55
0
6
SF Bay Area
I have apistos, corys and cardinals in my tank. At times when my CO2 has been too high I have never seen any of them gasping at the surface. Too much gas affects the larger fish first, my corys become really sluggish and if there is enough gas just roll over on their sides until I aerate the water. I have seen the apistos do the same thing. The other symptom I have noticed is that certain fish will freak out and swim wildly around the tank if they are stressed from too much gas. I don't think there are any tests that give a definitive answer, you really need to watch the fish since different species will react differently, or not at all, given a certain level of CO2 saturation.
 

ibnozn

Member
Mar 7, 2008
46
0
6
You can measure the ratio of ph to kh. There's a calculator here:
Measuring CO2 levels in a Planted Tank

My fish get sluggish and sit on the bottom. My shelldwellers hide in their shells. Their breathing becomes much more pronounced, I can see their mouths open and close as they breathe. My Oto will shoot up and snatch a quick gulp every so often.

I caught it at 100+ppm once according to that calculator, luckily just in time and was able to bring it down and add o2 fast enough to save the tank. They seem to start stressing at around 50ppm +/- and some species more so than others.
 

VaughnH

Lifetime Charter Member
Lifetime Member
Jan 24, 2005
3,011
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Sacramento, CA
That calculator is very good for when you are working with distilled water, to which you add only bicarbonate of soda and CO2. Otherwise it isn't of any value. When the calculator says you have 100 ppm of CO2 you may have 10 ppm of CO2. If you use a drop checker with distilled water, having enough bicarbonate of soda added to get a KH of 4 dKH, in the bulb, with 2 or 3 drops of bromothymol blue pH reagent, it will be green to yellow green when you have about 20 to 40 ppm of CO2 in the water at the spot where the drop checker is mounted. You do have to allow about 2 hours for the drop checker to reach an equilibrium with the tank water. The only more accurate way I know of to measure CO2 in the water is with a $2000 special CO2 probe.
 

bienlim

Junior Poster
Nov 16, 2007
2
0
1
this happened to my fish as well when i adjusted my co2 to a higher level


captain_bu;32884 said:
I have apistos, corys and cardinals in my tank. At times when my CO2 has been too high I have never seen any of them gasping at the surface. Too much gas affects the larger fish first, my corys become really sluggish and if there is enough gas just roll over on their sides until I aerate the water. I have seen the apistos do the same thing. The other symptom I have noticed is that certain fish will freak out and swim wildly around the tank if they are stressed from too much gas. I don't think there are any tests that give a definitive answer, you really need to watch the fish since different species will react differently, or not at all, given a certain level of CO2 saturation.