UV-Resistant HDPE Shade Balls for Reservoirs and Water Storage

Shade balls float on an open water surface to shade it from the sun. Covering a reservoir with them blocks sunlight and UV from reaching the water, which holds back algae growth and the light-driven reactions that can form unwanted by-products in treated drinking water, and the same cover cuts evaporation and keeps out birds, dust, leaves and other debris. They are used on drinking-water reservoirs, tailings and process ponds, fire-water and industrial storage, and any open body of water that needs shading or protecting.

Both come from covering the surface. Algae need light to grow, so shading the water starves them of it and curbs algal blooms without chemicals. Evaporation happens at the exposed surface, so a floating layer of balls blankets most of that surface and slows the loss of water to the air, which matters most in hot, dry and windy conditions. The balls do this passively, for years, once they are spread on the water.

A solid shade ball is light and simply floats, which is fine on a sheltered reservoir. A shade ball with a hole can be part-filled with water so it sits lower and weighs much more — around 240 grams filled against 40 empty — and that extra weight keeps it from being blown across or off an exposed, windy reservoir. Where wind is a concern the water-fillable type is used; where the water is sheltered, the solid ball is simpler.

It goes by the surface area. At 100 millimetres across, it takes about 116 balls to cover a square metre of water, so you multiply your reservoir's surface area in square metres by roughly that number for the quantity. A cubic metre holds about 1200 balls as shipped. Tell us the surface area or the dimensions of your reservoir, and we will work out the number of balls and the packing.

They are made from UV-stabilised HDPE, the same food-grade family of plastic used for water pipe and food packaging, and are widely used on potable-water reservoirs for exactly this reason. The UV stabiliser lets them take constant sun for many years — often a decade or more — without going brittle or breaking up, so once they are on the water they need little attention. For a potable supply, confirm the grade meets your local drinking-water approval.