[surgeonfish]

I have gotten away from using chemical test kits for calcium. I don't know how accurate they are. My Pinpoint calcium monitor got wet in November (stupid me). I temporarily went back to the old test kits (none were expired). I was not sure where my calcium levels were. I tried three different kits and was getting such a wide range of results.

Nov 19:
Instant Ocean 390 ppm
Aqua Pharm 500 ppm (480 ppm repeat test)
Nutrafin 560 ppm (560 ppm repeat test)

Nov 24:
Instant Ocean 390 ppm
Aqua pharm 440 ppm (500 ppm repeat test)
Nutrafin 540 ppm (540 ppm repeat test)

I compared two test kits to the Pinpoint 100 ppm calcium calibration solution and the 1000 ppm calcium calibration solution diluted 1:1 with RO/DI water which had a Ca of 0 ppm.

Standard 100 ppm ca solution:
Aqua pharm 120 ppm
Nutrafin 120 ppm

Standar 500 ppm ca solution (1000 ppm solution diluted 1:1):
Aqua pharm 500
Nutrafin 540

Unfortunately, I have never used the Salifert ca kit and therefore cannot comment on it.

After a few weeks I broke down and bought a new Pinpoint ca monitor and my gastric ulcers have healed. I would recommend you consider spending the extra money on an electonic ca monitor (or ask Santa Claus) as I have lost faith in the chemical test kits. No use having test kits you cannot rely on.