And youve tested it against the salifert, and it is accurate????
ALL test kits are going to have a degree of inaccuracy, as well as user error....
IMO, any and all test kits are more meant to just give you a baseline idea. none of them are truely good enough to give EXACT numbers every time without variation
Never used the salifert but it seems very quick and easy. If I'm just getting a general idea, I prefer quick and easy than tiny filters and 5-10 minutes of dripping. That said I normally use the Coral Shop potassium kit. Its from Europe and is also sold out at my LFS. That kit gave me dead on in a comparative lab test and 5ppm off in a second test. Truly excellent kit. I would order it right from the company but with shipping and exchange it comes to $120. I love it, but not for $120.