I have all 3. Red sea sucks. I used a couple tests and had it so long it expired. API is not much better. And I have everything salifert now. Get very accurate and consistent results. Sorry, but if you want good tests, its gonna cost ya.
buy the salifert tests on ebay. make sure it is listed as new as well. i got a phosphate salifert test kit that was new for $15 shipped, if you find a vendor that has them cheaper and you can comebine shipping for all of them it is worth the investment.