Making sense of Phosphate readings

[asylumdown]

well what's weird is that I've always run GFO and have had very low phosphate for the entire life of the tank. However, I haven't had the ULR test kit for very long, I was using the regular hannah checker which would routinely show me having no phosphate. But now with the ULR kit, I'm not sure if my results are 'real' or if they're the natural variation in responses I'd get from not doing the test exactly the same each time.