In this video, we will calibrate the EXO Total Algae sensor for Phycoerythrin in RFU. You can also use the EXO Handheld or the Kor Mobile App.
Just a reminder, the Total Algae sensor can measure both chlorophyll and either Phycocyanin or Phycoerythrin. For instructions on calibrating chlorophyll, please be sure to check out that video!
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 cup, guard, and wiper brush just for calibration to limit contamination. We recommend performing a two-point calibration. You want to use distilled or Deionized water for the first point since neither has particles that will fluoresce.
We filled our cal cup up to the first line from the bottom with DI water. Once the sensor is submerged, I like to give it a few taps 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 Phycoerythrin in RFU to calibrate. Kor Software will indicate if readings are stable in real time on this graph. Make sure the readings are near 0.
Once the readings stabilize, we’ll click apply and proceed to the next calibration point. Click to add another cal point. Since this is a two-point calibration, we’ll remove the sonde from the first standard and dry off the sensor guard and sensors.
For the second calibration point, we’ve prepared a Rhodamine dye standard solution with a concentration of 25 ug/L. Please check out our video on mixing Rhodamine Dye solution for information on standard preparation for this calibration.
We’ll immerse the sensors in the standard solution and give it a tap to clear any 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 this calibration, our solution is around 22 degrees Celsius, which is 45.0 RFU. And we’ll make sure this number is in Kor.
We’ll wait for the 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 cal.
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. Chlorophyll must be calibrated separately.
Please check out our other EXO University calibration videos, and thank you for watching.