Hello, I have always been using api testers and then upgraded to salifert. But I want to get a phosphate Hannah checkers. But on BRS they have 3 kind which are phosphate ultra low range PPM then the. Phosphate low range colorimeter, and the last one phosphorus ultra low range. I want to know which one will be the best choice for me to check my phosphates.. since I don’t have much knowledge in them. If anyone can help me I would greatly appreciate it!