KurtG wrote:

I don't think my Red Sea Phosphate test will go under .1 ppm. I've
tried it with distilled water and I still get the 0.1 ppm. It seems to
be the color of the reagent the comes out of the bottle.

Any recommendations?

--Kurt

I've never got a reading below 0.1 with mine either......I checked it
with a Nutrafin kit I had lying around and that gave me 0.25 so I'm
guessing the Red Sea one is correct in detecting a trace of Phosphate -
I've had the Nutrafin one down to zero after adding some Green X
Phosphate remover....

Gill