Alkalinity: API vs. Salifert vs. DIY

[reefsmurf]

Thought this might have been of some use to a few of you to know how accurate the API test kits are.

I bought a brand new API Alkalinity test kit, and compared it to my old Salifert and also using Greg's muriatic acid test (pH probe tested with new 4.01 solution and results calibrated). Here are the results:

Tank Water
Old Salifert: 5.8dkh/2.06meq/L*
DIY: 6.22dkh/2.22meq/L
API: 7dkh/2.5meq/L

Freshly mixed IO
Salifert: 10 dkh/3.5meq/L
DIY: 10.78 dkh/3.85meq/L
API: 11-12dkh/4-4.3meq/L

*unfortunately my alk doser kicked in right before I went to get water so this reading is very slightly higher than it should be. I tried to grab water from the other end of the tank where there is little flow

 

[Greg Hiller]

>Greg's muriatic acid test (pH probe tested with new 4.01 solution <

sounds like you are doing the right thing here, but just to clarify, the titration is to a pH of 4.2.