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Frequently Asked Questions

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Scientific

The ECO-PAR, due to the nature of PAR sensors, cannot be accurately calibrated outside of the Sea-Bird facility. However, there are some functionality tests that can aid in pre-deployment. A bright flashlight can validate whether the instrument sees light at all.
On a bench test one should see between 1000-4000 counts normally with the instrument in the white cap standing up on the benchtop. Use a terminal program to see the raw counts, such as Tera Term, and point a flashlight beam near the white cap. Doing so with a functioning unit will cause the counts to go to approximately a couple of thousand in a hair trigger fashion. It should be possible to decrease the counts on a properly functioning instrument by cupping ones hands around the white cap to shield it from light. It should be easy to get a response of a couple of hundred counts total in doing this. In the field if you shine a flashlight beam directly into the optics will see low level ambient light and it is easy to regulate the output in counts at the low end of the range (less than 1000 counts) when it is functioning normally. If your unit is not properly functioning, it will go from 50-ish to a couple of thousand counts and it will be very difficult or impossible to get an output of a couple of hundred counts. While the ranges of the response may differ between PAR models, these tests can be used with other PAR sensors to verify operation.

There are two optional modifications that can be done to your 9p at our facility (during service or as part of your original order) that will allow the 9p CTD to operate in freshwater deployments. The 9p’s pump will not operate in freshwater without these options.
First, the Modem Pump Control, allows you to control the pump directly, bypassing the requirement for it to see a certain conductivity frequency to activate. (On other CTD’s we can change this conductivity value to allow both freshwater and saltwater).
The second option is the freshwater contact pin, an optional pin modification that allows for the detection of fresh water by the 9p.

Field Procedures & Deployment

The ECO-PAR, due to the nature of PAR sensors, cannot be accurately calibrated outside of the Sea-Bird facility. However, there are some functionality tests that can aid in pre-deployment. A bright flashlight can validate whether the instrument sees light at all.
On a bench test one should see between 1000-4000 counts normally with the instrument in the white cap standing up on the benchtop. Use a terminal program to see the raw counts, such as Tera Term, and point a flashlight beam near the white cap. Doing so with a functioning unit will cause the counts to go to approximately a couple of thousand in a hair trigger fashion. It should be possible to decrease the counts on a properly functioning instrument by cupping ones hands around the white cap to shield it from light. It should be easy to get a response of a couple of hundred counts total in doing this. In the field if you shine a flashlight beam directly into the optics will see low level ambient light and it is easy to regulate the output in counts at the low end of the range (less than 1000 counts) when it is functioning normally. If your unit is not properly functioning, it will go from 50-ish to a couple of thousand counts and it will be very difficult or impossible to get an output of a couple of hundred counts. While the ranges of the response may differ between PAR models, these tests can be used with other PAR sensors to verify operation.

There are two optional modifications that can be done to your 9p at our facility (during service or as part of your original order) that will allow the 9p CTD to operate in freshwater deployments. The 9p’s pump will not operate in freshwater without these options.
First, the Modem Pump Control, allows you to control the pump directly, bypassing the requirement for it to see a certain conductivity frequency to activate. (On other CTD’s we can change this conductivity value to allow both freshwater and saltwater).
The second option is the freshwater contact pin, an optional pin modification that allows for the detection of fresh water by the 9p.

Oftentimes one will see data in their cast that looks erroneous or out of spec, but reviewing the timeline of each cast and the events which transpired can explain these jumps. If you are starting your cast while your CTD is on deck then the time during which the unit is running in air can be spiky or erratic, but this should be solved after the unit has been fully submerged and the pump has activated. The pump on time setting controls how fast the system will turn on the pump after deployment, so filtering out your deckside data can be done by calculating the number of scans to exclude using your pump on time setting, samples to average setting, and native sampling rate of your CTD.

Bubbles in the flow line can also cause spikes in your data towards the start of your deployment if the system isn’t able to normalize at the surface. We typically recommend units stay near the surface for 2-5 minutes in order to allow air bubbles to escape.

Finally, for additional resources in troubleshooting and smoothing data outliers for your CTD data, refer to our documentation on Seabird University.

 

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