Nitrate calibration solution or calibration standard is needed to calibrate meters for extra precision.
Nitrate 2000 ppm calibration solution that will last up to 300 calibrations of LAQUAtwin meters. Equivalent solution of HORIBA calibration solution Y045H. 
We recommend calibrating your LAQUAtwin meters daily (if you measure daily) or after every 10 measurements within a single day if you are testing more intensively.
 
⚫ Volume: 60 ml bottle with a twist top cap
⚫ Standard solution concentration: 2000 ppm (2000 mg/L) of Nitrate (NO3-)
⚫ Can be used to calibrate the meter at 34 ppm of NO3-N
⚫ Compatible with HORIBA LAQUAtwin NO3-11 and B-743
⚫ Made in USA