Milwaukee instruments PH pen PH600 works as described. I bought this pen to test the PH of the nutrient solutions plant. I removed it from the package and noticed White mineral building at the base of the pen. I can only imagine, but I would say that this accumulation is from the pen being tested before packaging. The pen was placed in simple tap water and left to sit for a few minutes. (I was told to let it sit for several hours in tap water, which was unnecessary). Test inside. 1 PH that occurred with the liquid PH test solution.
From what I've been able to collect the pen tip must always remain moist and never be left to dry. This is almost impossible to achieve with the pen CAP on. I decided to leave the instrument in plain tap water during storage.
The pen feels cheaply made but works fine so far, worth the price and an excellent alternative to a PH meter 75-100 dollars.
