Red Sea PH test

[Shultz]

I have one of the hanna's, bought bottles of 7.02 & 10.1 from hanna themselves here in the UK, 250ml bottles that should last longer than the tester itself LOL!

Cheers Shelton.

 

[Brisc0]

Calibration usually holds 6 - 8 weeks, though you should start to varify it after 4. I have worked with lots of PH probes back when I was into ground water cleanup, and I seriously doubt there is a probe that needs no calibration, however technology changes daily so who knows!