Danner Mag Drive Pumps are magnetically driven and thus use no oil and have no seals to wear out. We use them in all of our breeding systems. Standard versions have a 9' grounded cord while pond versions have a 18' grounded cord. Impellers for a given model number fit both the standard and the pond version. Flow rates are for the pump with 0 feet of head. Increases in pumping height will reduce flow rates. Charts will be listed shortly showing the change for each pump. In the mean time, feel free to call us at 248-840-2135 if you have questions about flow rates at give heights.