Using co2 in a fish tank. Is it safe?

[Harvardsquare]

I'm new to this website but I really need someone to help me out on this one. I have a 55 gallon that is established and has been up and running for about a year now. The ph has always been a high around 7.8-8.0. I know it is better to maintain a stable ph, but I'm looking to do some breeding and want to try to get it down to around 7.2. I have read adding co2 to your tank will lower the ph. I have tried this and it seems to work but I don't want to add to much. I read to much can suffocate your fish, so I was hoping someone could tell me what is to much. I have no live plants yet but plan to get some soon. Thanks.

 

[OrangeCones]

Contrary to myth, CO2 does not suffocate fish as it does not displace O2.

Too much CO2 CAN lower the pH too much, and that crash in pH can be deadly to fish. As you already have pointed out, stability is the key.