What is the process of replacing used diatomaceous earth powder with fresh powder called?

The correct term for replacing used diatomaceous earth (DE) powder with fresh powder is pre-coating. This process involves applying a new layer of DE to the filter which is essential for maintaining effective filtration. When a DE filter is backwashed, accumulated debris and used DE are removed from the filter, which necessitates the addition of fresh DE to ensure optimal filtration performance.

Pre-coating helps to ensure that the filter operates efficiently by creating a fresh layer of DE that can capture particulates effectively, allowing for clean water to circulate back into the pool. This is a critical maintenance step that contributes to the filter's ability to trap contaminants and maintain water clarity.

Backwashing, while important, pertains specifically to the process of cleaning the filter by reversing the flow of water, which helps to remove dirt and debris but does not directly involve the addition of new DE powder. Similarly, filtration refers broadly to the overall process of removing impurities from water and does not specifically encompass the action of adding fresh DE. Recharging is not a standard term used in this context, making pre-coating the correct choice for this process.