Honestly the more I think about it I think it was the PO4 kit that gave me the most trouble. That probably led me to lose some confidence in the NO3 kit. Either way I've had great results from Salifert and I think it is pretty easy to read.
@drawman this was my experience as well.
Reeferoo, what was not quite right about salifert kits? I wouldn't put much faith in what API kits read. Have you tried the salifert kits since your tank is done cycling? I have never once had a bad kit or had any inconsistant results. I would have to make an error myself to get a bad read. I have been using them for 10 years.
@Pedoconfuego Hopefully this helps clarify my position.
The Hanna Checkers, Phosphate and Phosphorus have always given me the same consistent readings, within a margin of erros, in relation to each other and after multiple test, so to when the Salifert kits would give me one result 2 times and another result a third time I had to abandon them.
As for Nitrate and Nitrite, I can read the Red Sea kits better than the salifert and with Nitrite I had the same inconsistencies as the phosphate kits as to where Red Sea I ran the same number of tests and results were consistent each time.
Originally I thought it was me making a mistake in practice or cleaning, but I hashed that out doing the same cleaning with RODI water for every test, taking water out of the return section of my sump. Checked expiration dates. The only thing I didn't do was have my wife check the test results, so it could have been just minor color variations that my my eye were defining as big swings. My wife and I have have constant "discussions" about what is Blue and what is Purple...she likes purple and according to here I seem to buy her a lot of really nice blue clothing...lol.
In the end I can achieve consistent results with the Red Sea Kits and Hanna Checkers I am using.
Edit...
Sorry missed the question about going back to Salifert...This is all still very new tank just finished cycling, So to answer the question, no, I have not gone back to the Salifert kit, but since the Red Sea and Hanna Checkers are working for me I probably wont.
As for the API kits, that was a LFS, they ran a couple of tests. Not something I am using for my purposes, they just confirmed what I was getting 2/3 times with the Salifert kits and the every time with the Hanna Checkers and Red Sea Kits.