Ca - Salifert says 270, Elos says 450

[Myka]

Tony, there have been a lot of complaints about the Hanna Calcium Checkers reading really high. I have always found Elos to read about 80-100 ppm higher than Salifert (the Elos alkalinity reads 1-2 dKH lower than Salifert). I have also found old Salifert kits (still within expiry) to be another 80-100 ppm lower than a new Salifert kit. I have no idea which one is more accurate, but I do know my tank is happier when I use the Elos kits and dose according to them. I have all but given up on Salifert kits for calcium and alkalinity. I need to buy some new Elos kits right away here, so it will be interesting to compare them to my old ones.

I'm trying to locate (it's a back burner project) some good independent calibration fluids for calcium, alkalinity, and magnesium. I hear they are out there somewhere.