the sponge needs to be either rinsed weekly or replaced with filter floss that is replaced weekly, or even removed entirely. if you put food in your tank, you want it to FEED things, not hang out in your filter and decay. pull out the bioballs and don't replace them with anything, especially live rock rubble. media like that traps detritus which causes nitrate and phosphate buildup. if you have to have something in that chamber, peel off a portion of the black tape on the back of the tank over the middle chamber and attach a small light, then put some chaeto in the chamber and you will have a refugium.