Hi Bella and welcome to the forum! I am not the DE filter expert, so I'll let someone else help you with your problem. I just wanted to say hello and thank you for becoming a subscriber. We appreciate it and it helps keep the forum online.

Regarding the red bold letters --- Sometimes when using pool chemicals, hazardous conditions can present themselves and using big, red, bold letters make sure that the reader doesn't miss the information that might prevent them from having a dangerous situation on their hands.