I would get the good phosphate test kit. Since PO4 is normally kept much lower than NO3 I find the PO4 test kits accuracy more important.should I get a good nitrate test kit or a good phosphate test kit first? I would like to get both but I can only get one for right now.
If you're getting 0 on the API test there is a chance you aren't testing correctly. I apologize if you know this already but if you don't shake bottle# 2 of the API test, and mean SHAKE it, it will read 0. I would shake it for a minute before starting the test and then again before you add the 10 drops. However, for a more accurate and easier to read test I would go with the ELOS Nitrate kit.haha I've had it up for 8 years almost and I've used the api test for all of those years and but ive been looking for a lot more accurate test because I'm doing sps and I have nitrates at 0 from the api test