[Deedledee]

I am trying different methods to determine how much c02 I have in my 32 gallon aquarium. Most recently I tried the 24 hour test .I degassed water and after 24 hours tested it against a sample taken at the peak c02 injection time. I am not too good at reading these API color charts, but it looks pretty close to the one point drop that is recommended. I do also have an in tank c02 detector, which is always a nice lime green about 2 hours after the c02 comes on. Is there another more reliable test ? I've seen the chart on the Rotala Butterfly site, but there is some confusion over that method as well ? What do you experts recommend?
Photo shows ph @ 4:00 pm today on the left & degassed sample from 24 hours ago on the right.

 

[Darkblade48]

I'd say it looks about right. Probably just under a single point drop in pH