What percentage of new greensand should be skimmed off during backwash and stratifying?

• A. 5% - 6%
• B. 8% - 9%
• C. 10% - 12%
• D. 15% - 20%

Answer: (B)

The percentage of new greensand that should be skimmed off during backwash and stratifying is typically around 8% - 9%. This range is significant for ensuring that the filtration system operates effectively while maintaining the optimal quantity of media that is necessary for proper function.

During backwashing, the goal is to remove any trapped debris and pollutants from the greensand, but it’s also essential to retain enough media to maintain the filters' efficiency and longevity. If too high a percentage is removed, the filter may not perform adequately, potentially leading to decreased water quality. Conversely, skimming too little may not effectively clean the media, which could hinder its function over time.

Understanding the balance in the backwashing procedure is critical for water operators. The chosen percentage helps to manage the media without compromising the entire filtration system's integrity, promoting both efficiency and sustainability.