Milwaukee PH Tester
PS: If you are in organic farming you will not really need it in principle.
The Milwaukee PH600 Compact Digital PH Tester is specifically designed to help manage the water quality in your grow space in the best possible way.
Results are fast and accurate with the digital LCD display.
Easy measurement: just place the probe in the sample, stir gently and wait for the reading to stabilize.
Simple 1-point calibration. It has a low energy demand for an extended lifespan.
Comes in a hard carrying case, with a calibration screwdriver and instructions. Batteries are included