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General Hydroponics™ uses the highest-quality reference solutions, allowing growers to calibrate many popular brands of PH, EC and TDS meters (NaCl scale or the 442 scale). General Hydroponics™ technicians check each batch to ensure that our solutions are precisely calibrated and yield reliable readings each time they are used.
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We currently ship within the US, with more countries coming soon.
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🇺🇸 Ship from USA · On Agora since 2026
$13.99