If you want a clearer pond, you may want to consider going soilless. Pond baskets will allow you to grow pond plants in the water using stones instead of soil. Pond water that does not have a constant amount of soil leaching in from submerged pots will look much clearer. Pond plants can live happily without soil, deriving all necessary vitamins and minerals from a pond fertiliser.
Remove the pond plants, along with their root balls, from the soil. Rinse the plants and their root balls under warm water, rinsing the roots completely of soil. Set the plants to the side on a piece of newspaper.
Set one plant in the centre of a pond basket. Holding the plant erect with one hand, place assorted-sized stones around the plant to hold it in place. The stones will also weigh down the basket, preventing it from floating up to the water surface.
Continue the process of placing one plant in the centre of each basket and surrounding them with stones, until each pond plant has a pot. Pour a 2.5 cm layer of pea gravel over the stones in each basket.
Submerge the pond baskets in water, with the foliage of each plant above the water line. You may need to set the baskets on bricks or concrete blocks to keep the foliage higher than the water.
Feed the soilless pond plants a diet of pond plant food or introduce some koi or goldfish to your pond, if they are not living in it already. Nutrients that the plants would have derived from the soil are given off as waste products by the fish.
Alternatively, line the baskets with three to four sheets of newspaper, set a pond plant in the middle of the pond basket and fill with untreated cat litter.