The aquatic circle of life is best performed with biological and mechanical filtration. Waste, and solids are removed before they decompose in the water that enters the biological filtration unit, and the mechanical system helps the process move along quickly so the need for chlorine or chemicals is eliminated, ensuring a natural ecosystem lake.

The mechanical portion of the filtration at Lake Wisconsin Dells is an enormous (add length, size, whatever is relevant) system that slows down the water velocity on the bottom to let dirt, waste and sentiment fall so that it can accumulate on the bottom. Then it can be filtered and easily removed. 

Oxygen is crucial to ensure the water is aerated and oxygenated and the lake debris (leaves, algae, sand, etc.) is swept away and collected in skimmer baskets. (The Crystal Cascades Waterfall performs this) 

The horsetail and waterlilies plants feed on the algae in the lake, naturally and effortlessly minimizing algae and help keep the water clean.

These creatures have a role in the ecosystem to feed on algae and effectively reduce its growth.

Create a natural-looking setting hidden in the lake's liner. They also provide a home for the beneficial bacteria that fall to the bottom and rest on the gravel and rocks. The bacteria go to work breaking down the debris in the water, cleaning and clearing the water.