Hanna checker off or is it the reagents?

[Lavabrine ninja]

I bought a ultra low phosphorous checker. I was told that it doesn't matter if I use ultra low phosphate or ultra low phosphorous reagents. It'll still give me an accurate reading. So, I got ultra low phosphate reagents. I tested the tank before a water change. Was reading 200ppm, I panicked. So, I quick did the water change (65% water change) then waited a day or two then tested again. Still showing the same reading. Is it because I'm using phosphate reagents in a phosphorous checker?

 

[Mr. Mojo Rising]

To me it doesn't make sense that "it doesn't matter if you use phosphate or phosporous", I wouldn't trust it.

But water change doesn't significantly reduce phosphate level, if at all. So it is possible to have the same reading 2 days after the water change.

 

[Lavabrine ninja]

To me it doesn't make sense that "it doesn't matter if you use phosphate or phosporous", I wouldn't trust it.

But water change doesn't significantly reduce phosphate level, if at all. So it is possible to have the same reading 2 days after the water change.

So I'd probably be better off paying new reagents that are ultra low phosphorous. And try and trade these phosphate ones