FAQ bbe AlgaeTorch

Yes, it is available as FTU.

We use a 2-point -calibration with Formazine standards. The range that AlgaeTorch could compensate the turbidity effects is 0-200 FTU. Although turbidity might be higher (standards are up to 4000 FTU) we focus on the range that affects chlorophyll measurement.

In general turbidity measurement itself can be rather different and the measurement affects accuracy and resolution. The AlgaeTorch uses small angle reflection - expressed in FTU. Intercalibration might be possible but is difficult.  It is difficult to sell the turbidity measurement as result of an extra sensor. However, there are no instruments on the market that use the turbidity measurement for the chlorophyll compensation.

You are right. Fluoroprobe does not record as Turbidity. For the Fluoroprobe we use transmission (like in a photometer) and in the results you will see the transmission. Nephelometry (like most turbidity sensors) uses 90° light scattering (FNU) or as in the ISO norm was described. In Algaetorch with using small angle reflection - expressed in FTU is measured but in Fluoroprobe, AOA, ALA only transmission is available as measurand.

- excitation wavelengths: 470nm, 525nm, 610nm, 700nm (Turbidity)
- emission window: 685 - 700 nm
- colour and intensity of actinic light: no actinic light

Yes. You can set it using the capacitive keys on AlgaeTorch setting menu.

With the standard 10s measuring time (default setting) the AlgaeTorch can take about 1100 measurements in continuous operation with a new fully charged battery. With older AlgaeTorches it is at least 700 measurements.

In time interval operation, a deduction of maximum 20% must be made from these measurement cycles because of the standby consumption. This means that a new AlgaeTorch can take 1,100 x 0.8 = 880 measurements in interval operation. With one measurement per hour, this corresponds to 880 / 24 = 36 days. For an old AlgaeTorch it is then approx. 23 days with one measurement per hour.

Yes, you can, but please consider the biofouling on the sensor body and also keeping clean the sensor eye. For this we highly recommend you to consider the hydro-wiper. It is a mechanical wiper which cleans the sensor eye automatically using its own battery energy.

With new batteries and a wiping interval of once every 2 hours, the Hydro-wiper has an operating time of 6 months. A wiping interval of 1 time in 2 hours is more than sufficient for most applications. Please consider for long term measurement in the water we recommend you to think about Fluoroprobe and AlgaeOnlineAnalyzer.

Not from the AlgaeTorch itself but from other bbe fluorometers yes, we have. As they are all adjusted to a reference fluorometer in the bbe workshop, the figures are transferable. A number of customers performed such studies. Surely there is a high variability as a mixture can contain big or small cells from the same class. Then the relationship is even sometimes very poor. For cultured algae the relation number of cells to chlorophyll is good once accurately determined.

No, if you starting the measurement with the bbe++ software, this will start a continuous measurement until you press the “Stop” button. So, the software will save and show all data that is collected until you stop the measurement.

Yes, you can charge the AlgaeTorch while measuring unconnected (normal way using the capacitive keys) as well as when the Torch is connected to a PC /bbe++. You can start measurements by using bbe++. The only thing that must be done is, that you have to start the measurement out of bbe++ not with the capacitive keys. Otherwise, the bbe++ will stop measurement while download data. Please note connecting AlgaeTorch only to notebook or computer will not charge it. You need to connect the main power adaptor to it.

Yes, there are some, first of all it is not recommended to leave the ATo/BTo in a dry room at temperatures above 45°C, as the batteries are very sensitive. They should not be exposed to temperatures above 40°C for longer periods.
Secondly, as the ATo/BTo’s transparent casing is made of polycarbonate, ethanol must not be used for cleaning, as this would cause it to become dull. We assume that isopropanol (<60%) can be used at room temperature (<20°C). The official cleaning recommendation is: clean water or mild washing-up liquid.

Chlorophyll fluorescence does not normally change this quickly. In general, algae need around 20–45 minutes to adapt to new light conditions. After this adaptation period, the measured values are usually expected to differ by only a few percent. This effect is related to the saturation of the photosystems, which affects how energy is processed and released within the cells. The very rapid changes observed with the Turner sensor therefore strongly suggest a background-light problem. For example, covering the aquarium immediately reduced the measured chlorophyll concentration. The AlgaeTorch does not have a problem with constant background light, such as sunlight. The background light is measured during each measurement and subtracted from the measurement signal. However, pulsed or rapidly changing light can cause interference. For example, fluorescent lamps can interfere with the measurement cycle. In this case, the background signal may no longer be correctly separated from the measurement signal.

Measurements under normal daylight are not a problem for the AlgaeTorch. However, the light should not be too intense. Very bright light or direct sunlight can saturate the photodiode, causing the measurement to become nonlinear.