Kind of like the trident reagents, they give you a little extra(in the case of the hanna it's 5ml extra), and using that last little bit, gives screwy numbers.
At 18 tests it should be fine. Can you run to an LFS and just get a salifert or redsea kit just to double check? I would most certainly be double checking before I made any changes.
At 18 tests it should be fine. Can you run to an LFS and just get a salifert or redsea kit just to double check? I would most certainly be double checking before I made any changes.