The TrolMaster pH probes provide accurate and reliable monitoring on the pH of the water being monitored by the Aqua-x. The PPH-2 probe is a commercially rated probe and it connects to the Aqua-x via the AMP-2. It is intended to be placed into a water tank. *All pH probes must be stored by using the storage cap and the correct probe storage solution. If a pH probe gets completely dried out, they will no longer function correctly. Any pH probe returned without the cap and in a "dry" state" will not be eligible for a warranty.