Are you speaking about the blue plastic pH probe included with the controller package/ If so, my probe in use for 6-8 months is now failing, loosing calibration. I was told at one point the included probe is a "starter" probe which I would not buy again.GHL probe really is the way to go, they last around 3x longer than anything else we have ever tested and have the fastest of reaction times which is highly important when using for a calcium reactor
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