Changing media in filter

[Clovis]

I have a tidal 55 hob filter on my 29g tank. It has a bottom layer of sponge, then back of ceramic and filter floss on top. 
 

how often should I change the sponge and floss?

side question, ever since I installed the filter the blue overflow indicator on the too is always showing. Even right after I clean. Any idea why?

[Dawn T]

I don't use filter floss in my HOBs, and the sponges never get changed. I just squeeze them out in a bucket of aquarium water occasionally to keep them from getting clogged up. I use coarse sponge, so it doesn't need much maintenance.

[FrozenFins]

Colvis I would replace one thing at a time. So one week you change out the sponge, I would replace it for a course sponge and then a few weeks later change out the floss.