Can Co2 really lower my ph this much?

[CleverBs]

So my tap water has a ph of 8.4, I have started doesing co2 over the last 2 weeks. I got a drop checker to make sure my Co2 was dosed correctly and it has been for the last week for sure (its when I got it). I checked my PH today and it reads 6.4...Could this be right? Using an API test kit.
having 6.4ph would be great and perfect for my tank so its not that im consurned with the ph levels but just didnt think it could change that much from Co2

Paramaters
Ammonia - 0
Nitrite - 0
Nitrate - 10
PH - 6.4

 

[meegosh]

Have you tried testing your tap water immediately and then let it set out overnight and then test again? I wouldn't be surprised if your pH was actually a lot lower than 8.4 to 'start' with.

 

[CleverBs]

no I havet tried this just always tested it right out of the tap.