Aqualytic AL400T-WL, Instruction Manual, Page: 20 / 32

20 AL400T-WL_2a 07/2011
2.3.2.3 Calibration Error
If the screen shown below is displayed after calibration, the
internal diagnostics have determined that the calibration
standards were bad or that they were inserted in the wrong
order. Either check the standards and recalibrate or restore
the factory calibration as mentioned below.
2.3.2.4 Restore Factory Calibration
If the above display appears and it cannot be corrected by
recalibration, the operator can restore the factory calibration.
Please note that the instrument may operate with reduced
accuracy until a new calibration can be performed.
Push and hold the [ ] key. Now push and release the [ ]
key then release the [ ] key. The instrument will turn off
automatically when completed. When the instrument is
switched on again the error message should be gone.
2.3.2.5 Calibration Standards
We recommend the following materials for calibration to achieve the accuracy stated in this
manual:
1. 1000 NTU Secondary Standards*
2. 10.0 NTU Secondary Standards*
3. 0.02 NTU Secondary Standards*
It is well known that diluted Formazin is unstable. If Formazin is used to calibrate the instrument,
ensure that fresh dilutions of Formazin are used only once to achieve the accuracy quoted for
the instrument. A Formazin Stock Solution Kit is available.
Secondary standards* with the mentioned values above have a limited shelf life of one year.
If secondary standards are used to calibrate the instrument, review the expiry date to ensure
that the standards have not expired.
*Secondary standards are a U.S. EPA (Environmental Protection Agency of the USA) approved
alternative standard to Formazin.
CAL
NTU
FNU
ERR