Why do my filters look like this?

[kr1st3n]

I have two cycled tanks right now, and for some reason, my Whisper 10i filter looks like this every 2 weeks or so. (Photos below.) It did this in my 3 gal, with one Betta, and it continued to do it when I switched it to my 5 gal.

At least once or twice a month I completely clean the filter housing, scrub it down, get the gook out of the intake, inside, etc... Is this normal? I've heard how some people reuse the filter to keep bacteria in, and just rinse off the gook, but it's impossible with this.

I mean, when I first pulled it out, I thought I had a snail death on my hands! It looks horrid! I do regular water changes, between 20-50% each week, and I clean out any extra food. I take out all the decor, clean off any visible gunk, etc... I just don't know what's going on.

 

[CAPSLOCK]

Looks pretty gooky for being cleaned so regularly (tank and filter). Is your source water funky in some way?

 

[upside-down catfish]

Do you squeeze the sponge in the dirty water(from the water change) to clean it?

 

[upside-down catfish]

I do regular water changes, between 20-50% each week, and I clean out any extra food. I take out all the decor, clean off any visible gunk, etc...

There shouldn't be any leftover food.