Wide Application: Test tap water, filtered water, distilled water, bottled water, well water, and fresh water. Widely used for all water quality testing, water purification applications, aquaculture, hydroponics, pool and spa, colloidal silver, water treatment, and more. Fast, Reliable, and Easy to Use: Simply dip the meter in, stir, and get results in seconds. No calibration or setup is required, you can use it right out of the box. Follow the step-by-step instructions below, checking the easy-to-read display. Easy to Calibrate: The pH tester is automatically calibrated at three points. You don't need any tools, just remove the protective cap and immerse the pH meter electrode in the solution. Press "ON/OFF" to activate the electronic pH, stir gently and wait a few seconds for the reading to stabilize. Pool pH Testers - Fast and Accurate Results: No need to work with colored folders and boring test strips. Resolution: 0.01 pH, Accuracy: ±0.01 pH. Lightweight and compact pocket pH