Hydro Vescence, effervescent cleaner removes tough build up in your pond and pondless waterfalls. The intense scrubbing action of the hydrogen peroxide naturally removes the build up. Hydro Vescence should be used at the first sign of build up to achieve the most effective performance. It can be used weekly, biweekly or monthly on ponds, waterfalls, streams and fountains. Hydro Vescence even sinks through water to treat the submerged areas.