Q&A: Unusual Test Bath Data – a Cautionary Tale

A Simple Mistake: Failed to Remove a Sticker

Most CTDs are shipped with some form of protection to keep debris from entering the conductivity cell. This is doubly important for instruments shipped with TBTO anti-foulant, which must be contained within the CTD’s flow path for safety reasons. In this case, a Deep SeapHOX V2 deployed in a test bath failed to match data from bottle samples and nearby sensors. Closer inspection revealed the cause – the shipping sticker was still in place, covering the intake of the CTD’s pump. Removing the sticker (shown in the highlighted region of the figure) allowed water to flow properly though the CTD, dissolved oxygen sensor, and pH sensor.

This might seem obvious, but the laundry list of deployment steps for even the most minimal oceanographic mooring can be daunting. It’s easy to overlook small details.