I use the hanna digital so far for phosphates and love it. Hoping to get the alkalinity one soon as well. I use salifert for nitrate, phosphates(on occasion), calcium, alkalinity and magnesium. I try to use the better ones for those as they are more reliable and easier to use than API.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.