i agree that if the bottom is dirty, then one possibly is overfeeding. The other option which I see in my lfs is to run an additional powerful external filter, once a week . The current stirs this up and then they remove this filter after about 4 hours. What I have tried to do in my tanks( i have 2 externals or powerhead in each tank ) is to make sure the current is less in one corner and then I suck this up with my water changes. Takes some time to work out the currents etc, but it works. Kuhli loaches are fine, but they are very slippery and fast fellas. I do nou use these. I keep corries in each tank, they swim and stir things up as well. cheers jk :thumbup: