Pinpoint Nitrate Monitor
 

http://www.jlaquatics.com/phpstore/s...uct_ID=pp-mno3
Hey guys! what do you think does this worth 300$?
Also,
Does this neds to be calibrated every time before measurement like Calcium monitor or just calibrate ocasionally?

Ok just got an answer to my own question:
http://www.americanmarineusa.com/NO3monitor.html

PINPOINT Nitrate Monitor has been designed as a precision spot testing monitor. Continuous Nitrate Monitoring may not be possible in most situations and may require frequent recalibration and probe replacement.