In this video, we will be calibrating the Total Algae sensor for chlorophyll in RFU. You can also use the EXO Handheld or Kor Mobile App.
Just a reminder, the Total Algae sensor can measure both chlorophyll and either Phycocyanin or Phycoerythrin. For instructions on calibrating those parameters, be sure to check out our other videos!
We are starting with our Total Algae sensor installed, as well as a Conductivity/Temperature sensor since the Total Algae sensor is temperature-dependent.
For best practices, we suggest using a dedicated cal cup, sensor guard, and wiper brush just for calibration to limit contamination.
Chlorophyll requires a two-point calibration. You want to use distilled or Deionized water for the first point since neither have particles that will fluoresce. We filled our cal cup up to the first line with DI water. Once the sensor is submerged, I like to give it a few taps and a visual inspection to make sure there are no bubbles on the sensor's face. If you have a clean wiper, you may also use that to clear any air bubbles on the sensor lens.
In Kor, we will select Chlorophyll in RFU to calibrate. Kor Software will indicate if readings are stable in real time on this graph. Make sure the sensor readings are near 0. We’ll click apply and proceed to the next calibration point. Click to add another cal point.
Since this is a two-point cal, we’ll remove the sonde from the first standard and dry off the sensors and sensor guard. For the second calibration point, we’ve prepared a Rhodamine dye standard solution with a concentration of 625 ug/L. Please check out our video on mixing the Rhodamine Dye solution for information on standard preparation for this calibration.
We’ll immerse the sensors in the standard solution and give it a few taps to clear the bubbles. Make sure you use the table in the EXO manual to determine the relative RFU based on the temperature of the second calibration solution at the time of calibration. For our calibration, the solution is around 22 degrees Celsius, which is 16.4 RFU. And we’ll make sure this number is in Kor.
We’ll want to wait for readings to stabilize before applying the calibration. Once the readings are stable, click apply. Now you will see the calibration summary screen where you can redo or complete the calibration. I’ll choose to complete the calibration.
If you prefer to measure in mg/L, refer back to these same steps and use the derived temperature-dependent standard value from the table in the manual. As a reminder, the Total Algae sensors are two sensors in one. Phycocyanin and Phycoerythrin must be calibrated separately.
Please check out our other EXO University calibration videos, and thank you for watching.