Co2 And Denisoni Barbs (oxygen Loving Fish)

[tanyauk]

Hello! I have 5 Denison Barbs in my planted tank (300l).
I started to diffuse CO2 and noticed that my barbs started to lose scales on top of their heads. I stopped CO2 and they seem better.
I have soft water and may be diffusing CO2 drops PH? I would like to have nice planted tank and also don't want to lose my fish.
Do I have to buffer the water? I have crashed corals in external filter to buffer a little bit. I don't know my water parameters, as I have no test kits at the moment.
Does diffusing CO2 cause irritation?
Thank you

 

[Liam]

If you already have soft acidic water the ph drop caused by Co2 may be making the water too acidic for them. I don’t know what water the barbs prefer. The crushed coral should be buffering the water, but you would need to test your water (for ph and KH) to see how low the ph is and how low the Co2 pushes it and then decide how much coral you need to buffer the water enough for the barbs. With normal levels of Co2 in the water (30ppm) even the most oxygen loving fish wont be affected by lack of oxygen. I expect that the scale loss is about the water being too acidic. I have never heard of this with Co2 so I am far from certain about what I have said.

 

[tanyauk]

Thank you for your reply, it's very helpful , I will test my water!