3rd Trident NP and it still doesn’t read phosphate!

painter1982 · Mar 1, 2026

I bought a Trident NP in September of 2025. Long story short, it says phosphate zero. Neptune sent new one finally around end of November. It won’t read phosphate. Gets stuck at whatever level its calibration is at. I used both calibration methods, Neptune fluid and Hanna checker method. I’m on the third NP. Just received it last week and installed it. Guess what? Phosphate reading zero. I have done everything exactly like they have told me. This thing does not work. Hanna checker phosphate in my tank is around .05 to .1, the NP is zero. Anyone have any luck with this $700 paperweight? If so, what did you do?

spartanman22 · Mar 1, 2026

I had a similar issue. My phosphate, per Hanna checker was <0.05. Trident kept reading zero. I eventually deleted, reinstalled the trident, and calibrated and finally got phosphate readings, but then my nitrate readings were artificially high by about 3x.

I’m guessing the LOQ for phosphate on the NP isn’t all that great which is why for low level readings it spits out zero.

I don’t think these products are really all that great. I’ve not had consistent or reliable results with the NP or ACM (both brand new out of the box). My ACM won’t read Ca/Mg despite not mechanical or line blockages. Alk is spot on though.

I’ve found with these units, that I only tend to get one parameter precise and accurate. The others either flat out don’t work or are way off.

winxp_man · Mar 1, 2026

Mine did the same. Then one day after a water change I forgot to turn on the water heater again. The next day my tank was down at 67*. I was at work a the tank had dropped from 78 over night and part of the morning. Got off early and made it back at about 1 o’clock. I was literally expecting dead animals in my tank.

Lo and behold nothing was dead, and all were very much alive. ticked but alive. But after my po4 had been showing 0 for the past week that evening it started reading correctly. And since this about 1.5 months ago the NP unit still reads correctly even after a reagent change. Don’t know what give in this instance.