Aquatron Pump The Aquatron Pump changed from MK II to Mk III style in July 1994. In the Certikin Spares List the MK II is referred to as ‘Old Type’ and the MK III as ‘New Type’. If the grey sticker on the returns end of the pump has a serial number ending in ‘N’ then it is a ‘New Type’ pump. It is possible to distinguish between ‘New’ and ‘Old’ impellors by measuring the dimension on the impellor of the inlet opposite to the thread. On an ‘Old Type’ impellor this dimension is 44mm and on the ‘New Type’ is 54mm. The only difference between the 1.5HP and the 2HP ‘Old Type’ impellors is the shape of the fins inside the impellor. On a 1.5HP impellor the fins are curved, and on a 2HP impellor they have a visible flat section. When ordering a capacitor for an Aqwuatron pump it is important to identify the type of motor. Is it a Lafert motor or a Certikin motor? A MK II pump has a Lafert motor and a MK III has a certikin motor.