Here is an old standby. The Tetra PF1 is an economical external pond filter. Removes ammonia and other polutants by biological filtration. Has a trickle flow action in whcih filtration media is submerged. Out of pond for easy access. Pre-filter sponges remove suspended debris to improve water clarity. Bio Ring provides surface area for beneficial bacteria. Interchangeable 3/4" and 1" intake fittings. 1.25" drain fitting.
This filter is designed for a maximum 500 gph flow rate and ponds up to 1000 gallons. It's demensions are 15.25" in diameter and 12.5" high.