After having all my fish die at same time, I emptied pond cleaned everything. I added some filter material from a friends aquarium, and bottled of quick start. I have 1 goldfish that was in a 10 gallon tank when die off happened. I just don't feel right using him to cycle pond. will stop at store and pick up a comet. Fingers crossed I feel like I need a old lesbian in purple robes to burn sage and chant over pond for luck.