can some show step by steps plz
Here is a video with step-by-step. Not for Srir x Apex, but for Siri x KHG.
Note that KHG is the world first reef hobbyist grade Alkalinity auto test device, and it is why my demo video include Alkalinity value (some PM me ask where I got my alkalinity value, and here it is).
Hopefully you can get the idea while checking my article here.