I have five fishtanks, from 125g down to 40g tanks - all housing African Cichlids. In each tank I installed a Ziss Bubble Bio Moving Bed Filter. I over filter all my tanks to ensure the best water quality possible. I purchased them in late 2018 and have been installed in each tank. I have been experiencing issues with them. The media has stopped moving and are all clumped together in the top of the filter. The amount of bubbles coming out has diminised substantially to a few bubbles per minute. The sponges are cleaned regularly - and when done - there is no change in performance. One filter I actually shook it - and it went back to clumped all together. Does anyone have any ideas how to get it moving again? Thanks.