Ira, I an amazed you have a problem with the 2213. We operate around 40 of this model on 100 litre tanks, which we clean routinely every 3 months taking 10 mins. They are still flowing well even when dirty. Do you operate with the baskets? We found that the water was not moving outside of these baskets and the water would stagnate down the sides causing plant collapse, hence going back to using the grills top and bottom with filter media inbetween. You are most welcome to give Steve a call (he is the expert) sometime and perhaps he can help you sort the problem out.