Yes i been using API for years just because i have a hookup and i get the kits cheap as dirt. They work but dont trust them. If i get a reading back that seems strange or not quite what i was expecting i recheck and then recheck with salifert kit. Ive seen some pretty crazy differences between the 2. The API color charts just have shades that match too closely and the jumps in reading are too much for example nitrates 0,5,10,20,40,80,160 the 0-20 range is the hardest to read and the most used so error is rampant.
The Master Reef kit has less problems but still inaccurate many times. I often use the API kits for regular testing and the salifert kits for monthly checking and ckecks on abnormal reading. Allows you to be accurate and save money.
29g Mixed Reef, 150w 14k Phoenix MH w/ Moonlights, Reef Octopus BH1000 HOB Skimmer, Ecotech Vortech MP10es, ReefKeeper Lite (Plus), PH Probe, Temp Probe, ATO, Carbon/GFO Reactor.