Cooling Tower Balls

Cooling Tower Balls (CTB) are a floating ball cover that controls algae by simply blocking direct sunlight. Eliminating sunlight by covering the complete water surface creates an effective shade factor to control the growth of algae. The pictures below show a case study comparison of 2 cooling tower systems from the same customer. One cooling tower system utilized CTB while the other system received no algae treatment. RSI has installed millions of CTB in cooling towers since 2009.

Starting Day

30 Days

60 Days



  • Controls Algae by Blocking Sunlight
  • Saves Energy
    - sump water is cooler in warm weather
    - sump heaters run less in cold weather
  • Safe for Water and Food Contact
    - HDPE plastic even meets FDA guidelines for food contact


  • Balls Rise and Lower with Water Level
  • UV Inhibitor Gives 10+ Years Service Life
  • Maintenance Free - Easy Installation
  • Made in USA - 100% Recyclable


Approximately 10 balls are needed per square foot of water surface.
5' x 10' sump = 50 square feet x 10 balls per square foot = 500 balls
10' x 10' sump = 100 square feet x 10 balls per square foot = 1000 balls
Note: Sizing so there are a few extra balls is fine.  The extra balls will simply start a second layer with added benefits.

Please contact RSI to have a free evaluation conducted on your system.