I don't get it, what are yo udoing that you need to change the pads once a week? I never seen such wastes accumulate before and I know I overfeed my smaller tank and even then it would have taken 3-4 weeks to require a massive cleaning. What you should do is change them in seperate intervals. Change one filter one week and another the week. Otherwise you won't have time for any bacteria to grow.
If the pad is covered with gunk where I can't even tell what color the pad was I won't bother to use it again, if it's just a light covering of gunk I'll just rinse it and re-use. That's what I do with the Whisper cartridges. No sure if Cascade has removable pads like theirs. There's no need to boil it or add chemicals to it hat might be harmful later.