Backwash procedures of Ultrafilter
1. Open the backwash intake valve, the wash drain valve and the backwash drain valve of the Ultrafilter
2. Start the backwash water pump and the oxidizer metering pump. 
3. 20 seconds later, close the wash drain valve, and backwash for 2 minutes.
4. When time is up, stop the backwash pump and oxidizer metering pump.
5. Close the backwash intake valve, backwash drain valve, open the wash drain valve and the wash valve.
6. The water from the wash pump is qualified. (generally, the wash time is 2 minutes.)
7. When time is up, close the wash valve and the wash drain valve.
8. The system is shutdown and is in standby state.