I drained my N. Pulcher tank down to about 3 inches and took out all of the plants and rocks. Thenk, I vacuumed the daylights out of the sand and scrubbed the glass quite well. Next, I set everything back up and refilled the tank. It was quite cloudy from stirring up the sand, of course. By this morning, the water had cleared and the three daffodils had reestablished their territories. Tonight, I noticed another cloud of fry in the tank. There is no way they were there when I vacuumed everything yesterday. They had to have hatched today, judging by their size and what took place yesterday, but I canÃ¢â‚¬â„¢t for the life of me figure out how the eggs survived the cleaning.