So I just figured out that my umbrella sleeves have a insert and cover with a rubber gasket that appears to keep dirt etc. out.
Currently mine are dry at the bottom but have cr^p (and maybe dried algae). Forecast is for rain tomorrow, should I just insert the covers and seal them up for the season or after rain tomorrow try and clean them out, allow them to dry and then cover. Thoughts are greatly appreciated.
EDIT - Is "cr&p" really a curse word? LOL