bluelab
Bluelab METCOM Combo Meter for pH, Temperature, Conductivity (Nutrient) in Water with Easy Calibration, Digital TDS Tester for Hydroponic System and Indoor Plants
Oakton
Oakton Instruments WD-35634-05 EcoTestr pH1 Waterproof Pocket Tester, 0-14 pH
Extech
10% off
Extech PH220-C Waterproof Palm pH Meter with Cabled Electrode
Apera Instruments
15% off
Apera Instruments, LLC-AI501 PH700 Benchtop Lab pH Meter, 0.01 pH Accuracy, 1-3 Points Auto Calibration, 3-in-1 pH/Temp. Electrode