Got some calibration solutions 4.01 and 7.01...some probe cleaning and storage solutions... My suspicions were well founded... My ph was reading 1.7 high so I was overdosing with PH DOWN... my Res ph was at around 4.9 so I added some fresh water to bring it up to around 5.8.... I've gotta say I feel MUCH better about checking my PH now.... I'd advise anybody to invest in the proper maintenance of their equipment, simply for peace of mind. :thumbsup: