Bluelab pH Probe KCI Storage Solution 250ml The perfect solution to store and hydrate your Bluelab pH products. Bluelab pH Probe KCl Storage Solution is made specifically for use with Bluelab pH products. It is designed to increase response time and maximize the life of Bluelab pH pens and pH probes. For best results, use the KCl solution to store the pH pen/probe after use and hydrate monthly. Bluelab pH Probe KCl Storage Solution is manufactured to high laboratory standards.