Flushing the Fountain
Two or three times during the summer, I clean out the line using three common household items (1) hot water, (2) vinegar, and (3) a turkey baster. (I might add that I originally tried to unplug the line with wire, but that was ineffective.)
I remove the hose (and attached mouthpiece) from the fountain and bring it inside. Using the turkey baster, I force a mixture of hot water and vinegar through the line. It takes a few flushings, but, eventually, clots of slimy algae are pushed out the house. I finish with multiple hot water rinses, until I’m sure the line is clear. Then, I reassemble the fountain and plug it back in.
When I’m ready to put the fountain away for the season, I’ll clean the pump itself, but just clearing the line gets me through the summer.