Hagen Test Kit
Does anyone have experience using the Fe and Ca Nutrafin test kits for freshwater? If so can anyone comment on their accuracy or recommend something better. I cannot tell the difference between the yellow/green on the GH API test and since I use 100% RO water I'd like to be able to know my Ca:Mg balance. As for the Iron I just found it an interesting thing to test for. Thanks in advance.