i have an AIO tank approximately 7Gal of water volume. Whenever i do the scrubbing of my inner tank, the algaes got scraped off the wall of aquariums. It supposes to get drained into my input chamber where it meets my floss and sponges, mechanical filter. but it just keep on spinning inside my tank, and refuse to get out, and lastly it sunk into the bottom of the tank. What can i do?