Use these to calibrate one of the cheap yellow PH pens shown here. I used to buy a new Ph Pen every growth streak, but now I can just calibrate it and save money in the long run.
Efficiently Test Your Antifreeze And Battery Acid With A 3-In-1 Refractometer
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π PH 1-14 Extensive Storage Testing Monitoring: Optimize Your Storage with Precise pH Level Monitoring
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π― Honey Refractometer with Automatic Temperature Compensation (ATC) - Tiaoyeer Moisture, Brix, and Baume Refractometer for Honey, 58-90% Brix Scale Range - Honey Moisture Tester
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80 Pieces Water Test Litmus Strips Litmus ph Paper Soil Acidity Meter Liquid pH Tester 1-14
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