This design of Bottom drain features an aerated ring; the dome has a ring of perforated hose that sits neatly on top.
Not only does the aeration benefit your pond and your fish but it also helps with pulling debris into your sump making it more effective.
The aerator on this dome is run the diameter of the Bottom Drain dome and is over a meter in length,1140mm to be exact. The aerator is fitted with an air input tee that will accept flexible airline with an internal diameter (ID) of 4mm.

This kit comes supplied with 10 meters of flexible clear PVC airline (4mmID-6mmOD)