stuff gets stuck in the gravel, we all know that. If you rinse the filter every few days with tank water, it will keep your water a lot cleaner than the normal way of doing things. I like gravel in my tanks, and use it in all of them. But like Danz says, I try to use very little in my flowerhorn tanks. Just enough to make it look nice, and clean often. If you have a bare bottom, the current will catch any debris and it will go into your filter, and as long as you rinse filter often with tank water, your water stays very clean.