The last few times I have mixed up IO salt, my calcium readings have been high. According to my Elos test kit, my freshly mixed SW had 420ppm calcium rather then the normal 350-360. I figured my test kit must just be bad so I went out and bought a second Elos calcium test kit(expensive little bastard...). My new Elos kit is reading 440ppm calcium on freshly mixed SW, and my old elos kit is still reading 420ppm. What going on?!? Are both of my test kits off by 60-80ppm? Or did IO change its salt formula(or did I get a bad batch)? This is driving me crazy! If my test kits are off by that much I feel sorry for the corals in my display.