In itself this is Mulmabsauger of Denerle a great idea for the Nano Cubes, but unfortunately you can only use limited him in very fine gravel. In very fine gravel it happens quickly in the suction that it is too high and there sucked clog Ansaugregulierung with the valve, which no longer allows a complete closing of the valve and so the water suction works only conditionally. Since you can clean this valve is very difficult, that was one reason to take this unit back.
