G greenmeds Active Member Sep 8, 2008 #1 do i have to calibrate my ph pen EVERY time i use it? or just so often
kpw555 Well-Known Member Nov 10, 2008 #2 You can just do it every week and that would be fine. Unless you drop it or the temp changes a lot then I would re-calibrate.
You can just do it every week and that would be fine. Unless you drop it or the temp changes a lot then I would re-calibrate.
