FAQ bbe AlgaeOnlineAnalyser

There is no specific minimum or maximum flow rate required for operation. The main limitation is the pressure inside the flow-through system, which must not exceed 0.5 bar above atmospheric pressure.

A flow rate of approximately 10 L/h is commonly used because this corresponds to the flow rate of the optional peristaltic pump typically used with the system.

Higher flow rates may also provide reliable measurements, but they can result in increased pressure, turbulence, or degassing within the measuring chamber. If the pressure exceeds 0.5 bar above atmospheric pressure, there is a risk that the glass measuring chamber may leak or be damaged. Therefore, higher flow rates cannot be recommended without corresponding test data.

For the optional AOA pump, the maximum delivery head is 5 m.

There is no fixed technical limit for the size of the database used to store measurement data. The practical limit is determined by the available storage capacity of the PC, such as the hard drive.

Very large databases may affect the performance of the AOA software, for example by slowing down the display or data handling. With a modern PC, this is generally not expected. If performance does begin to decrease, the automatic archiving function can be used to reduce the size of the active database.

Yes. The AOA control software provides an automatic archiving function under Measurement | Options → Database.

You can define:

• how old data must be before they are removed from the active database, and
• up to which date the archive file should additionally contain data.

This function prevents the active database from growing indefinitely while keeping older measurement data available in archive files.

When exporting data, you can specify a time range, for example from 06/02/2026 18:00 to 07/02/2026 18:00. The selected measurement data are exported to an .aoa file, which can then be opened in the AOA software.

All measurement data within the selected time range are included in the exported file. However, when the file is opened, the time-axis scaling does not automatically correspond exactly to the selected export period.

Use the available navigation functions, such as View | Select Range, to adjust the displayed time range and obtain the desired time-axis scaling.

The power consumption depends on the operating components:

• Chlorophyll Sensor: minimum 3 W (12 V / 250 mA)
• Cleaning piston: additional 9 W when running (12 V / 750 mA)
• Pump: approximately 12 W (12 V / 1 A)

When both the cleaning piston and pump are operating, the total power consumption can be approximately 24 W, in addition to the sensor's base consumption.

The Chlorophyll Sensor uses two different detectors:

• Fluorescence: Chlorophyll fluorescence is detected using a photomultiplier. An optical filter in front of the photomultiplier allows light around the chlorophyll fluorescence wavelength of approximately 680 nm to pass.
• Transmission: Transmission from all excitation LEDs is detected using a photodiode. The photodiode does not have an optical filter because it is designed to detect the different LED wavelengths.

The Chlorophyll Sensor uses the following excitation LEDs:

• 370 nm
• 470 nm
• 525 nm
• 570 nm
• 590 nm
• 610 nm

Unlike the FluoroProbe, the Chlorophyll Sensor does not have a 700 nm LED for transmission measurements.

The LED Brightness parameter is primarily used during the LED tuning and presetting procedure. It defines the brightness used for the F₀ measurement relative to the brightness used for the concentration measurement.

A value of 100% means that the same LED brightness is used for both measurements. Lower brightness settings require a longer measurement time because the lower light intensity results in a higher relative noise level.

The F₀ measurement represents the fluorescence measured under very low background-light conditions. Ideally, F₀ would be measured without any background light.

For modern FluoroProbe instruments, however, the required LED brightness control is performed automatically and essentially in parallel with the measurement. The “LED Brightness” value is therefore not used during the actual measurement and has no further relevance for normal operation.

The value can nevertheless be set to 20% in Online mode if required.

Algae that have been exposed to sunlight need some time to adapt to the light conditions inside the measuring chamber before a reliable F₀ measurement can be taken.

The lower the light intensity used for the F₀ measurement, the longer the required adaptation time.

If the measured Genty value varies significantly during the day, for example due to changing sunlight conditions, it may be necessary to increase the F₀ adaptation time.

Algae that have been exposed to sunlight need some time to adapt to the light conditions inside the measuring chamber before the measurement.

The lower the light intensity, the longer the required adaptation time.

If the algae concentration or measurement conditions vary during the day due to changing sunlight conditions, the F Adaptation time may need to be increased.

F Measurement is the measurement time used to determine the algae concentration.

At low algae concentrations, the measurement time can be increased to improve reproducibility and reduce the influence of measurement noise.

The Number of F Measurements parameter determines how many F measurements are performed for each dataset. Depending on the application, it can be used in two ways:

• Operation with a pump: When a pump is used, the measurement cell can be refilled between individual F measurements. The refill time is defined by the “Refill Sensor” pump time. This allows the sample in the measuring cell to be renewed between measurements and helps reduce sedimentation effects, particularly during longer measurement periods.
• Averaging of multiple measurements: If Number of F Measurements > 1, several F measurements are performed for one dataset and averaged. From more than 3 measurements, the “Erase Outliers” function can also be activated. This function excludes outliers from the calculation of the average according to the defined outlier criteria.

For a detailed description of these functions in Online mode, please refer to the relevant section of the AlgaeLabAnalyser manual.

The Cleaning Interval defines how frequently the measuring chamber is cleaned automatically. A cleaning interval of approximately 6 hours is recommended to prevent biofouling in the chamber.

A shorter cleaning interval results in more frequent cleaning and therefore increases the operating frequency of the cleaning device. This can reduce the maintenance interval of the cleaning mechanism.

A Tune LED Interval of 1 is recommended. This means that the LEDs are tuned before each measurement to compensate for changes in LED output.

If very fast measurements are required and the interval between measurements is short, the tuning frequency can be reduced by selecting a higher interval value.

The values represent the signal measured for each LED using ultrafiltrated or deionised water without algae. They serve as the reference signals for the respective LEDs.

These values are determined and set automatically during the Calibration / Offset procedure.

The DA value is determined automatically by the instrument during LED tuning. It is primarily relevant for service and diagnostic purposes and normally does not need to be adjusted by the user.

The Transmission Coefficient is used to compensate for the influence of turbidity on the measurement. By adjusting this coefficient, the effect of reduced light transmission caused by turbidity can be compensated for in the measurement results. The recommended setting and adjustment procedure are described in the AlgaeLabAnalyser manual.

For the instruments in question, the typical accuracy of determination is approximately 0.015 µg/L total chlorophyll-a. Therefore, total chlorophyll-a concentrations in the range of approximately 0.2–0.5 µg/L are generally within the expected confidence level.

However, a high concentration of yellow substances can affect the accuracy of chlorophyll-a measurements. The higher the concentration of yellow substances, the greater the potential influence on the measurement.

If the yellow-substance concentration is constant, and the offset has already been calibrated using filtered water, the yellow-substance calculation can be deactivated in the Fit Parameters before the next measurement. In this case, the instrument uses the previously determined offset of the filtered water, and the accuracy stated above can be expected.

For recalculating or refitting previously recorded measurement data (*.aoa), please refer to the AOA manual.

No. Standard solutions for calibrating fingerprints are not available.

There are also no additional standard fingerprints for algae classes where the fluorescence characteristics are sufficiently similar to an existing fingerprint. For example, Chrysophyceae can show fluorescence characteristics very similar to diatoms. In such cases, an additional standard fingerprint would not provide a meaningful distinction.

If an algae group showed a sufficiently distinct and reproducible fluorescence spectrum, it could be considered for inclusion as a separate standard fingerprint.

Regular maintenance is recommended to ensure reliable operation and prevent blockages, leaks, and contamination of the measuring system.

Weekly maintenance

• Check the inlets and drains for blockages.
• Check the instrument for leaks.
• Clean the hose system.

Monthly maintenance

• Clean the measuring cuvette.
• If a pump is installed, replace the pump tube.

Every six months

• Replace all other hoses inside the instrument.

Please check instruction manula and also below youtube tutorial:

https://www.youtube.com/watch?v=ozdm6vDnmys