how much CO2 is deadly?

[Jman17H]

For a while now I have been doing DIY CO2 in a 30 long with 3 two liters and I could not get above 20 ppm so earlier in the week I added a 4th bottle and have tested the past 2 nights for pH & KH and determined I am now in the 40-45 ppm range.

I run a limewood airstone into a powerhead so I get real good difusion. I try to change out 2 bottles each week.

My fish seem to be acting normal but should I be worried that this will be 2 much for them in the long run?

 

[Purrbox]

You should be well within the safe range. If you fish were going to have problems with the CO2 levels you would see it already. It's not until you get up over about 100ppm that you're likely to have problems as a result of the CO2 levels.

 

[MSU Fan]

at 150ppm (stupid co2 tank dump), I lost a couple of hatchets, 1 rainbow, and bunch of other fish looked pretty bad. After quickly remedying via removal of co2, adding airstones and aiming my powerhead at the surface, all was better very soon.

 

[Peyton]

I have something similar to your setup but I have a 40gal. 4 DIY co2 bottles with two changed every week. I have had no problems to speak of.

 

[Jman17H]

I just knew that most people shoot for 30 ppm and I wanted to make sure there was nothing bad about 40.

I guess most people probably shoot for 30 when doing presurized so that the plants have enough but they are not wasting gas.

 

[Lonewolfblue]

I personally shoot for 50-70ppm myself, but do have a tank where I have it between 35-50ppm. Like Purrbox said, there's usually no problems up to about 100ppm. When getting close to 100ppm, then you need to monitor more closely and watch your fish.

 

[malkore]

I've held 45ppm for months without any fish deaths or visible signs of stress.