If you're looking for a simple, quickly and accurate way to measure the pH of your fish tank, this UP AQUA handheld pH pen tester is perfect for you! Pre-calibrated for your convenience, these testers are ready to use straight out of the box- simply remove the end cap, turn on and insert into your tank water for a reading in seconds. Capable of testing your fish tank pH from 0.0 to 14.0, getting an accurate reading and ensuring perfect water and tank health has never been easier!