Calpump's stainless steel and bronze pond pumps are very reliable. Typically used in Koi or goldfish ponds to power filters and waterfalls, they can also be used with mid-size to large fountain nozzles. The S580, S900 and S1200 gph models have a 3/4 MPT intake and a 1/2 MPT outlet that easily accommodates 3/4 flexible tubing. All of these models must have either a screen or foam pre-filter attached to the intake. We highly recommend using the MAN foam filters. These pumps can easily be connected to biological filters, ultraviolet sterilizers, ultraviolet clarifiers and in pond filters.