You are here:   HomeSupportFAQsQ series SensorsOn our CTD is a sensor that has a white sphere, which we guess is the sensor, and it has a black cap with a hole on the top. Now the question is whether this cap needs to be removed or kept on during the observations.

Frequently Asked Question

On our CTD is a sensor that has a white sphere, which we guess is the sensor, and it has a black cap with a hole on the top. Now the question is whether this cap needs to be removed or kept on during the observations.

A black plastic cap is provided to protect the Teflon diffusing sphere during storage and transport. This protective cover must be removed before taking any light measurements. We also suggest that you periodically check the "dark readings" by taking data with the cap on to check the baseline.

Note that in the cap, there is a small hole as a vent, in case you decide to do a profile with the cap on to look at the dark baseline. You can also do this by checking a profile made at night.