Such was the case, yesterday. I had decided that the fountain looked so nasty with all of its green fungus that I really should clean it! I got out my little shop vac and removed all of the water and debris. It still had stains and little presents from the local birds. I mixed up a solution of vinegar and a little Dawn dishwashing detergent. I got out the stiffest scrub brush that I could find and I began scrubbing. I thought that I had done a pretty good job. I added a little water to rinse. Again, I used my shop vac to remove the clean water, added a little more water and repeated the removal of the water. Then I just left the hose in the fountain to fill it up. I walked to the other side of the garden to turn off the water. I turned around and there were hundred of bubbles overflowing my fountain. It was really amazingly beautiful! I could not help myself, I just started singing Bub-Bub-Bub-a-ling! I have been told that neither vinegar or Dawn will harm the birds so I may leave it.