Name: Paul Anguiano Richland, WA (Zone 7a) GW & DG: tropicalaria
Might the goop be biological in nature? Bacterial films and algae matrices can appear anywhere there's constant water. A little bit of bleach added at intervals, or other microbialcide, would prevent and clear that type of build up.
Mid-Columbia Gardens Geodesic Greenhouse
Years ago my mother used to say to me, she'd say, "In this world, Elwood, you must be" - she always called me Elwood - "In this world, Elwood, you must be oh so smart or oh so pleasant." Well, for years I was smart. I recommend pleasant. You may quote me.