Could a dirty skimmer sponge be keeping my nitrates high?

[Cheebs]

I've had my reef tank for a few months now. So far nearly everything has been perfect, except that my nitrates are always sitting at around 10, and sometimes 15 ppm. I think part of this is my feeding. Should I be feeding little chunks of food at a time and wait for the fish to eat it before adding more? They all freak out when the powerheads are off and I can't seem to be able to get them used to feeding with them off.

Anyways, I haven't changed my sponge filter in my little overflow box for my filter since I've had it (thats a few months). I know I'm way overdue, so I was wondering if a the nasty filter could actually be the cause of my higher nitrates? I've otherwise maintained everything else very well, and I know water changes aren't the problem, and I've got live rock to boot. I just never clued in to change the filter media.

Thanks!

[boxfishpooalot]

anywhere you find organics(fish poo, uneaten food, detritus, dead anything) you will have bacteria on it producing nitrate/phosphate.

Yes that sponge filter of your is producing nitrates. Do a test if you dont belive me. It can be fun too. Make some new saltwater. Take off the foam filter. Dry it off by shaking it well. Now put it inside that newly mixed saltwater. Wait one day. Test the nitrates in the bucket of water. You will see that they rised. O yea test before and after and aerate the water too.

[bertoni]

Changing the sponge might help. I don't think it'll hurt.