So I’ve had these test kits from my last reef before I drained it and moved out of state. Some of the bottles says it expires 5/22 and 4/22 for the PO4 and NO3. The calk,mag, and KH says 6/22. my question is are they still viable.
Who knows. These test kits must degrade gradually presumably and not overnight on an arbitrary date. If weekly test results ‘seem OK’ and the results match one’s observation of the DT then that may be a good guide. I bought the same kits recently and found one of the droppers to be useless and some of the colours hard to distinguish. My new Salifert test kits seem more idiot proof. But then I may be wrong!