Generally speaking it is better to keep your collector clean, than have to clean it.  In this case, for in-water profilers, a rinse with fresh water while the instrument is still wet from deployment may suffice, and using a soft cloth or paper towel to blot (not scrub) the collector to remove most water residue is all that is required. However, this is not always possible. With C-OPS and XRR profililing systems we supply lint free optical cleaning tissues and Purasol lens cleaner which is non-toxic and non-damaging to the optical materials we use, and is non-flammable and thus not subject to travel restrictions like other substances like alcohol. When Purasol is not adequate and does not visibly remove the residue that must be cleaned, other methods are listed below depending on the collector type.  When using detergent, be sure to completely rinse the collector so no soap residue remains which can have variable spectral transmission.

Teflon-covered irradiance collectors should be cleaned with gentle detergent such as Dawn dishwashing detergent and water or alcohol, but no stronger solvents or abrasives, along with a soft cloth, tissue, or KimWipes. Do not use stiff brushes and do not use abrasives.

Irradiance collectors that are constructed of Acrylic such as QCP-2XX0 and MPE-PAR should be cleaned with gentle detergent such as Dawn dishwashing detergent and water. Alcohol may damage acrylic and should not be used.

Regarding radiance windows, the window for C-OPS, XRR, and legacy PRR/PUV systems is quartz (not plexiglass) and can be cleaned with mild soap and water or alcohol. Again, do not use abrasives or stronger solvents. Radiance windows for BNF PNF profilers are made from acrylic and alcohol should not be used.

Note also that quartz windows will stain if salt water drops are left to dry.