Ok, I've been struggling for a while trying to keep my calcium up so I finally got frustrated and bought a different brand test kit to jic. Well my Seachem kit came with a reference sample and I used that to make sure I was using the kit properly and I was. Today I bought a Nutrafin kit and tested it against the Seachem ref sample and it's way off. My water tests 400 on the nutrafin and 300 roughly on the seachem. Who do I believe? I wish I had a known reference or something.