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Note from the Director: Cyanobacteria Monitoring
In the Spotlight: AlgaeWatch "Spring-Bloom" Special
Jim's Corner: SCUFA Analog Output Settings
Instruments In Action: SCUFA Helps Make Lake Profiling More Accurate

Technically Speaking: Optimizing the Acccuracy of the Cyclops-7 Fluorometer
Cyclops-7 Update: SCUFA and Cyclops-7 Comparison Data Collected in the San Francisco Bay
Cyclops-7 Update: Dye Tracing Study in Sycamore Springs, Alabama
Noteworthy: 10AU Data Logger Software Download for Windows
Upcoming Events: View Our Upcoming Tradeshows

TD News Archives: View the Archives


fluorometerCyanobacteria, a.k.a. Blue-green algae, are common forms of photosynthetic bacteria present in most freshwater and marine systems. The monitoring of cyanobacteria is of growing interest in a number of research and monitoring fields. Of particular interest is the monitoring of cyanobacteria as a public health risk. As the rates eutrophication accelerate due to human impacts on aquatic ecosystems, algal blooms are becoming a more common problem. Many species of cyanobacteria produce toxins generally referred to as cyanotoxins. In a cyanobacteria bloom, these toxins can cause health risks to humans and animals and the real-time monitoring of cyanobacteria can serve as an early warning system for potentially hazardous conditions. Drinking water sources, recreational lakes, ponds and coastal areas are all susceptible to the impacts of cyanobacterial blooms.

The US EPA has listed cyanobacteria onto their Water Contaminant Candidate List and currently list cyanobacteria as an unregulated water contaminant.

A few more useful links on cyanobacteria toxins

In addition to the dangers of cyanotoxins, the water resource industry has an additional interest in cyanobacteria because of their production of two compounds, geosmin and MIB (2-methylisoborneol) which cause taste and odor problems in drinking water. On-line fluorescence sensors can replace or reduce the need for manual cell counting procedures and can be used to trigger tests to evaluate taste and odor, cell identifications or the presence of toxins in a water supply.

Cyanobacteria are also of interest to basic researchers. Cyanobacteria has been found to be a numerically abundant faction of the phytoplankton community. Their roles in primary production, community structure, and spatial and temporal distribution are of interest for numerous scientific studies as well as natural water monitoring. Since chlorophyll fluorescence cannot be used to accurately determine cyanobacterial presence, analyzing phycobilin concentrations is essential for detecting, quantifying, and monitoring cyanobacterial levels

Cyanobacteria have two unique accessory pigments that can be detected with a fluorometer; phycocyanin and phycoerythrin. Phycocyanin is the predominant pigment in freshwater systems while phycoerythrin is the dominant pigment in marine systems. Each of the pigments has a unique fluorescence signature and when considering purchasing a fluorometer, a decision must be made as to which pigment is appropriate for the environments you wish to monitor.

Due to the excellent sensitivity of Turner Designs fluorescence sensors, it is possible to have true early warning detection system that can identify an increase in cyanobacterial growth in natural waters before it reaches a dangerous level, providing managers and technicians valuable time to take necessary measures.

Turner Designs is proud to offer cyanobacteria versions of the submersible and field sensors in the coming month. Whether you are interested in an on-line AlgaeWatch system to detect phycocyanin in a drinking water plant or a submersible or handheld unit for phycoerythrin detection in marine systems, we will be able to meet your research and monitoring needs. Please contact our This e-mail address is being protected from spambots. You need JavaScript enabled to view it for details on availability, pricing and lead times.

Yours truly,
Rob Ellison
Director of Sales and Marketing


Turner Designs AlgaeWatch Fluorometer "Spring-Bloom" Special

fluorometerSpring blooms are bad news for suppliers of drinking water. The growth of taste and odor causing algae may bring a flood of customer complaints about their water quality, causing you to spend much more time monitoring, and trying to figure out how much treatment chemical to add, and when.

Turner Designs' AlgaeWatch fluorometer is designed specifically to help you minimize these problems, and for the next 60 days, when you purchase an AlgaeWatch fluorometer you can take 12.5% off the price, (US Customers). To get your discounted price, use the promotion code "Spring Bloom Special" when placing your order. International customers should contact their local distributor for country specific discounted prices.

This e-mail address is being protected from spambots. You need JavaScript enabled to view it today to learn more about the AlgaeWatch On-Line Continual Monitoring fluorometer, or visit our website.

Effective dates of this special promotion are April 15 - June 20, 2004


fluorometer Jim McCormick, our Tech Support Manager, has been with Turner Designs for over 15 years and has extensive expertise with our entire line of instruments.
"Jim's Corner" will feature common questions that provide a better understanding of the operation of our units. Please feel free to send your technical question to This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

We use the SCUFA to monitor in-vivo Chlorophyll a levels by recording the Analog output signal. How can we confirm that we have the Analog output is set for the best dynamic range and resolution?

The SCUFA allows the user to set the 5 volt Analog output level for a corresponding Fluorescence reading. The user should set this value to give them suffcient maximum range, but not so high that the reading resolution is compromised. For example, if you expect to get Fluorescence readings that may go as high as 100 on the SCUFA, then set the 5 volt level to equal 100. You can then determine the reading resolution by dividing the value of your setting by 4,096. So, for the setting of 100, this will give 0.0244 for the reading resolution.
As another example, in oligotrophic environments, a lower setting of 20 could be used and this would give a 0.0049 reading resolution.

See section 3.7 in the SCUFA User's manual for details.



SCUFA Helps Make Lake Profiling More Accurate

fluorometerChlorophyll in a lake, a simple test? There are some problems to think about before one begins to the process of determining the amount of chlorophyll in our natural water. Most investigators would open "Standard Methods for Water and Wastewater" to get the professional opinion for technique. There are several methods that might be employed in this situation. Water across the Earth contains wide variations in chlorophyll concentration making choice of method important. In Southern Oregon, for instance, lakes in the Oregon High Cascade mountains are exceptionally pure containing 1 to 2 ug/L of chlorophyll. At Crater Lake National Park, researchers wasted time using the spectroscopic method for determining chlorophyll before it was noticed that the concentration was way below the detection limit for that method. Today the fluorometric method is used with a lower detection limit.

Once the method is settled upon, the problem of collection is considered. How deep in a clear blue lake does one go to collect and identify the chlorophyll profile for a lake? At Waldo Lake in Central Oregon, the lake is 120 meters deep at our study station. A lake clarity reading for the lake on September 21, 2003 was measured with an eight-inch diameter Secchi disk and was 36.0 meters using a surface viewing tube (the lake surface was disturbed by wind). The thermocline was between 14 and 30 meters.

With this information a scheme for collection of chlorophyll grab samples might be conceived. One might want to collect several samples in and around the thermocline to document algal productivity in that important zone. In this pure water lake there is concern surrounding benthic productivity and so samples mid-lake and lake bottom may also be collected to check this hypothesis. But this is just a guess. Where are the primary producers, the algae, in this lake? Grab samples may miss entire strata of species comfortably making a living in the lake. An in situ chlorophyll probe is the answer. Turner Designs has developed the SCUFA, a Self Contained Underwater Fluorescence Apparatus. The SCUFA was used by the author during the summer of 2003 to document the entire chlorophyll profile of the lake for the first time.

The Turner Designs SCUFA was physically coupled to the working Hydrolab Datasonde III and both units programmed to collect data every minute. Therefore together they collected depth, temperature, oxygen concentration, pH, conductivity, redox potential, turbidity and the in situ chlorophyll fluorescence signal. Water samples of 500-mL were collected, filtered, extracted, and chlorophyll concentrations determined using the in vitro fluorometric technique (and a Turner Designs digital bench fluorometer, Model 10-AU). The results indicated that there was good correlation between the extracted values for chlorophyll using the in vitro fluorometric method and the in situ fluorometric data. The relationship between the two was calculated to be:

in vitro Chlorophyll Concentration (mg/L) = 0.0139 * SCUFA Signal + 0.0492


This data set had a correlation coefficient of 0.888. This relationship also suggests that the SCUFA can measure in the range of 0.1 ug/L chlorophyll at its detection limit (this value is twice its zero value calculation). The SCUFA could be calibrated to show a closer relationship to the in vitro chlorophyll values however its use in this lake was to determine its sensitivity to the very low concentrations of chlorophyll in this very clear High Cascade lake.

Reviewing the Waldo Lake SCUFA profile and the grab sample chlorophyll data suggests that a chlorophyll layer has indeed been missed. The increase in chlorophyll below 80 meters increases much more rapidly than the grab samples would suggest. The SCUFA shows a sharp peak at 80 meters where there was no grab sample. Instead this peak shows up at 100 meters, the depth of the closest grab sample. Also the shape of this deep chlorophyll maximum may appear very different using the grab sample data, while the SCUFA data suggests that it has some structure between 80 and 100 meters.

The Turner Designs SCUFA has been shown to be a very useful and sensitive in situ instrument capable of helping discover and design water collection schemes to identify chlorophyll in our natural waters.

John Salinas
Environmental Chemist
Grants Pass, Oregon, USA



fluorometerTechnically Speaking, It All Adds Up…
is a series of articles for people who want to obtain the best possible results from their fluorometer. This month's article will describe how to maximize instrument accuracy by characterizing the response of our newest sensor, the Cyclops-7; and then how to use Microsoft Excel to display the trend-line for that sensor, and conveniently display the concentration level in the correct units. (The procedure can be applied to any sensor with an analog output).

Customers using the Cyclops-7 fluorometer will need to characterize the relationship of its analog output voltage to known concentration levels.

Then, by inputting the correlation data into a spreadsheet program such as Microsoft Excel, you can easily display the trend-line and conveniently display the equivalent concentration level for any sensor voltage output.

Step 1 - Measure a Blank Sample
Generally speaking, this is very straightforward and simply requires measuring the sensor output voltage when the optical end is immersed in a beaker of de-ionized water. (Note that for best possible accuracy and consistency, you should use a 1L glass beaker on non-reflective surface, ensure the sensor is at least 3 inches above the bottom of the beaker and center the sensor in the beaker). Record the output voltage for the blank in a spreadsheet program such as Excel.
Special care must be taken when working in oligotrophic oceanic (low productivity) environments. Much of the ocean contains very low chlorophyll concentrations, and in these situations accurately measuring the blank can make a big difference.

For additional information, see "The Blank Can Make A Big Difference In Oceanographic Measurements" by John Cullen and Richard Davis. Limnology and Oceanography Bulletin, Volume 12(2) June 2003

Step 2 - Measure some known samples
Goal here is to use 2 or 3 known concentration levels spread over the measurement range of the instrument.

This is very straightforward in the case of tracer dyes, such as Rhodamine WT.
If working with chlorophyll, it will be necessary to do extractions to correlate chlorophyll concentration levels to equivalent voltage outputs.

Record the output voltage for the known concentration levels in the same spreadsheet as the blank reading.

Step 3 - Use Excel to determine the output voltage/concentration level relationship
Enter the data for the blank and known concentration levels into a spreadsheet.
Then use Excel to create an "XY Scatter" chart. Now you have 2 choices to create the "calibration curve" for the sensor.

Method 1 uses the "Trend Line" function in Excel. This will generate the "best fit" straight line for the points plotted, plus show the equation for the line, see example below. This equation can be used to convert any subsequent sensor voltage readings to equivalent concentration levels.

Method 1

Method 2 is based on drawing a straight line between each of the data points. This will take into account the effect of the blank at low concentration levels and the onset of quenching at the upper end of the measurement range. In this method, to convert voltage readings it is necessary to read the equivalent concentration from the chart

Method 2

The above procedure described how to optimize the accuracy of the fluorometer itself. There are many more "best measurement practices" that should be used as part of the procedure to obtain the best possible overall accuracy when measuring your samples.

For more information on getting the best possible accuracy, please visit our website.


SCUFA andCyclops-7 Comparison Data Collected in the San Francisco Bay
fluorometer fluorometer
Data collected from side-by-side SCUFA and CYCLOPS-7 submersible fluorometers deployed in San Francisco Bay since February indicate that CYCLOPS-7 continues to impress in real-world applications. The data from the two instruments correlates very well. The CYCLOPS-7 is the ideal sensor for integration into multi-parameter systems where size, power draw and cost are of concern.

Cyclops-7 Dye Tracing Study in Sycamore Springs, Alabama

Another CYCLOPS-7 customer used the sensor in a dye tracing study in Sycamore Springs, Alabama. Below is a description of the study and thoughts on the sensor.


The Cyclops was attached to a CR21X data logger and was powered continuously from the internal bank of 8 D-cells. The program used measured fluorescence at all three scales every 5 seconds with 1 settling time and was averaged every 5 minutes (60 readings).

The stream (about 15-20 L/s) was ponded with a small dam and the cyclops positioned looking down into about 20 cm of water. There was initial slight turbidity arising from redirecting the flow upstream to mix and enter the pond.

About 600g of Rhodamine WT (20%) was injected in a small stream in a cave (Ben's Den) on the south side on Monte Sano Mountain immediately East of Huntsville. Sycamore spring (actually two distinct adjacent springs) was located about 600 feet lower and about 1 km away, probably running along the strike of a small fold.

Tracer emerged in a beautiful well-defined breakthrough curve, peaking at ~8h. The attached figure shows the results. This is consistent with the observation that continuous monitoring prevents many of the spiky anomalies that can plague grab sample breakthrough curves.

"The general design of the sensor, cable etc is great. The cable is first rate for field use. "

The 12v power consumption is light, so it ran fine for 24 h on 8 D cells.

"I think the Cyclops represents a major step forward in field fluorometry, and provides a truly portable dye trace and stream gauging sensor. "


10-AU Data Logger Download Software for Windows.

Turner Designs announces availability of a Windows-based Data Logger Download software utility for customers with a Model 10-AU equipped with an internal data logger. The new utility replaces the DOS-based version previously available, and provides the following improvements over the DOS version.
1. Better selection/control of the COM port on the PC used for the data transfer.
2. Data transfers can now be executed under Windows, there is no need to open a DOS window.

Customers can download the utility at no charge here.

Or visit our website at,

Go to the section titled: Model 10-AU Internal Data Logger Software, new Windows Version 2.1, and download the file titled

Installation information is provided on the link page to the above file.