Sadly, you'll never get an actual reading since the algae is consuming all of the nitrates.
Then is it really a problem?
Isn't that the idea behind an ATS or refugium, to have the algae consume the nitrates and phosphates before they reach detectable levels?
Does that then mean that you cannot trust your water tests as well because you are employing an ATS?
Not trying to be difficult Sniper, but in a way you are contradicting yourself.
either algae is a good way to export excess nutrients or it isn't.
If it is, as evidenced by the use refugiums and ATS, then the only concern here is the aesthetics of the algae in the main display and preventing it from impacting corals, correct?
I've seen ATS setups that grow pounds of algae in a weeks time, so are you implying that those setups have horrible water quality as well, or is it only whenever the algae grows where we want it to that it is ok.
I agree that the presence of that much healthy algae warrants a closer look at water quality, but does it really matter beyond personal preference where the algae grows, as long as it is not encroaching on the corals and other livestock in the tank.