28g HQ1 Filter question

[hudaisy]

I have a 28g HQ1 and am running it with all the filter media (rings, carbon and sponges) I also have 25lbs of live rock. The tank has been up a little over 2 months and it is time to start filter changes. My question is this: I know I need to change the active carbon bag, however, I also see growths (almost like a collection of hermit crab skins or brine shrimp) on the top of the sponge. Should I change the sponge filter, too? My LFS (very good, btw) said not to change the sponges as they have good bacteria. However, I am fairly certain that these growths are not good.
Please help!

 

[blayz77]

you can replace or rinse out the sponge. pour some ro water into a bucket and shake it around in the ro water.
the ceramic rings are the only filter media you dont replace as that has all the bacteria and stuff thats good for the system.