the ca test from salifert is pretty simple it's get 2ml of sample, add scoop of #1, 8 drops of #2, shake, then add #3 drop by drop til the color changes from pink to blue. i looked up the directions for the mg test and it looks like they are the same, i don't do the mg test as often so i didn't remember exact instructions, but i can do the ca test in a little over a minute, so i would definitely recommend salifert, having used both salifert and seachem, among others. haven't personally used elos, so can't say anything about that.