ive just started to make a large bio filter,its about 1200 in height 600 wide...i was thinking of a ball valve in the side at the bottom to let out solids...with a 100mm pipe down the middle to the bottom from the pump,and a milk crate to hold it up right, so water can rise up through the media then return to pond....i was thinking of bio balls and pot scrubers for media....could i use shade cloth as well.....and how fast should the water enter the filter....any other input would be great...