Thx, I do have good Ca and Alk kits. Just my Mag has expired. And my tanks have allways been low on CA/Mag. Doing randy Holmes-Farley's instructions here
http://reefkeeping.com/issues/2006-02/rhf/index.php#9
Just added a little yesterday, about to check Ca/Alk this morning. Everyting looks same as last night, which is good, no crashing.