Question: When cleaning filter foam blocks, bleaching doesn't work

[Cakebaker13]

So, I had an accident with an anemone awhile ago. Well, after manually cleaning my canister filter's foam pads which were white, they have remained a stained yellow.
In an effort to get the back to new, I tried bleaching them. However, it is not working at all. The pads aren't changing colors.
I wondered if anyone else had experience with this? Can anyone explain why this is happening?

They are the fluval canister foam filter pads, for what it's worth.

 

[mcgyvr]

You need to replace them..
Bleach actually seems to harm them (makes them sticky/dissolves the foam some,etc..) from my experience of trying to do that once to them..

You can wash them really well but the "yellow" won't come off/go away..

 

[Cakebaker13]

You need to replace them..
Bleach actually seems to harm them (makes them sticky/dissolves the foam some,etc..) from my experience of trying to do that once to them..

You can wash them really well but the "yellow" won't come off/go away..

Thanks! I will do that. I was becoming baffled why nothing was happening.