1. VIVOSUN Digital pH Meter Pen Tester for Water & Hydroponics $8.55
2. Hanna Instruments HI98103 Checker pH Tester $46.99
3. Hanna Instruments HI98107 pHep pH Tester $64.99
4. Bluelab pH Pen $99
5. Apera Instruments PH60 Premium Series Waterproof Pocket pH Tester $110

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