I’ve always stored the probes for my EC meter in distilled water. But I recently met a grower who had some issues with the strength of his solution. I asked how he stored the meter, and it turns out he wasn’t keeping the probes in water, and when the meter was replaced and stored properly, the issue was resolved. So I thought I would pass along a friendly reminder: Always keep your PPM meter or EC meter or PH meter probes constantly submerged.