For what kit? the elos kits are very nice, but don't give resolution that salifert does. I use both kits - I use elos to do quick approximate tests, and then salifert if I want to verify or get a more accurate number. Eg - elos Mg resolution is 100ppm unless you double the directions. What is salifert, 10ppm?
If just doing a quick check, I don't care what Mg reads as long as it's between 1200-1400 or whatever. But when I do my monthly testing of eveyrthing, I sit down and get a more accurate reading with other kits, usually all of them to compare against each other because I really don't trust any single test kit.
Either way, the Elos readings have always matched LaMotte and Salifert (I've only used Mg, kH, Ca by elos).