Magic, increase water flow throughout the tank. DSB are made to take lots of feeding if set up correctly. Feeding "the tank" results in increased populations of microfuana. I dump food in my tank. I have no DSB or microfauna predators. Lots of detrivores. You need to scour the internet looking for places that sell sand detrivores. A variety of nass snails are excellent, spagetti worms, ceriths, the bristle worms that come on your LR, etc. And, get water circulation going in every corner of the bottom. There is a method for setting up and maintaining a DSB and you really need to strict to that method or your sand bed will be weak.
