I'm new to pools altogether.
Just recently when I turn off my pump, I hear an immediate gushing of water. Dirty water and DE go into pool from main drain and there is visible de in my skimmer. There are small air bubbles in my intake area (but they have been there since we moved in-no changes). What are your suggestions? What should I check? My filter is an old Nautilus FNS. Thank you in advance!