I use red sea and it sucks, but then again I only check it twice a year at best. Once to see where my mag is at, then adjust it manual dose, then it gets replenished by my calc reactor and it never changes afterwards.
I plan to do quarterly ICP but if I’m being honest.... The eye test on coral and tank health. I focus on trends of my cal, alk and ph. I don’t get into other elements. I’m a more laid back hands off reefer other than those.
I wanted to try that one but I couldnt find it on Amazon. I know BRS and MarineDepot have them but Its really the only thing i need. So i dont want to buy anything extra to get the free shipping and then with reg shipping it comes to to about $25
None are fantastic but practically speaking it really doesn't matter. Through normal coral growth a tank that consumes 0.8 meq/l per day in alk (about 2.25 dkh so a high consumption tank) will consume150ppm mag per year assuming zero water changes.