I have both and they are somewhat difficult to use. MG less so than the CA checker, but I’d probably get salifert for both unless you just really want to add them to your collection.
If you decide you still want them, I have a fairly new ca Hanna checker with most if not all of the reagents that I’d sell you at a good price. Just pm me.
They are of use for like monthly testing to confirm your levels are in line if your using 2part or a reactor. More of a impulse buy when you having nothing at the moment to blow your money and just want to collect them all and become Royal Crown Chin Tester Master……Ooohhh
I have them and use them. The Ca test is finicky in that a very small error can skew the results drastically, in my experience.. You just have to make sure that you get the measurements correct on the samples. I’ve been able to get consistent readings that way. I trust the accuracy of it compared to previous levels and adjustments I’ve made by adding Ca, it gives me predictable results.