first pic shows inner parts of the chambers, the white container on the left is the 'static' chamber which will contain kaldness k1 media,the media will stay 'static' until cleaning when it will be fluiised by an air ring in the base of the chamber. (second pic)
on the right of the first pic is the pipework in the second chamber (the moving bed) left hand pipe takes water from 'static' chamber right handpipe is outlet to pump (Ehiem 1250) This chamber also has an air ring which is always on except for cleaning time when it is turned off to allow detritus to collect in the bottom of the chamber pic three shows grid, pipework and air ring.
the fourth pic shows the full assembly as it will go into my sump with the pump connected to the outlet on the right
just have to cut slots in the white container and the top 2" of the pvc pipe
for water flow