Well, that totally depends on what you want the filter to do. Do you want a prefilter to keep the pump from clogging? If so, then you want one of these: http://www.tetra-fish.com/pond/products/filtration/water--garden-garden-pump-pre-filter.aspx or http://www.tetra-fish.com/pond/products/filtration/submersible-flat-box-filter.aspx. They come with a short piece of tubing so if you wanted longer tubing, you'd need to buy that by the foot, and you would need hose clamps. The larger box filter will filter small ponds up to almost 500 gallons.
If you want to filter the pond, and have a waterfall, there's this one: http://www.tetra-fish.com/pond/products/filtration/waterfall-filter.aspx. You'll need several feet of tubing to go from the pump to the falls, usually the pump is at the far end of the pond, and hose clamps.
If you simply want to have the most filtration possible, then there's: http://www.tetra-fish.com/pond/products/filtration/clearchoice-biofilter.aspx. You pump isn't large enough to handle a pressure filter, but this filter is an excellent biological one, and one of my favorites. Again, you need tubing to run from the pump to the filter inlet, and hose clamps. This is a gravity filter so it must sit in such a way as to let water travel back down the outlet tubing to the pond.
Let me know if you have any other questions!
Date published: 2018-06-13