When it comes to a medium like water, there are many possible root causes of problems and treatment methods. While both biological and chemical water treatments will do the trick, a simple yet commonly overlooked solution is maintenance. A simple weekly or monthly vacuuming session will remove leaves, sticks and sludge clumps from the water. This is an effective way to control nutrient loading right at the source. There are various models and ranging in performance from start-stop machines to continuous operation designs. The model you will need will depend on factors such as presence of trees and new organic deposits in the water, pond size, depth, and frequency of maintenance.