It sounds like your getting some odd reading BL. Try diluting your sample (new) in half, and do it again, if you haven't tried that one yet. How old are the tests? IF you don't get the answer here, try Saliferts forum on RC. He answers quickly usually.
I really don't like the seachem CA test, I always got wack readings from it
With the salifert kits, are you leaving the bubble in the tip of the syringe? It really makes a difference IMO to lave it in there.
I had a heck of a time keeping my ionic balance right for years, untill I decided to got bare bottom and minimal LR. Sand beds really do suck up buffer IMO.
