Marlene, the filter will work in the sense it will remove turbidity - just as it did for a swimming pool. However, whether or not you replace the sand with new sand won't matter in the long run. First, the pressure drop across the sand bed is high (compared to biological filters and other systems often used for ponds) which requires a much higher horsepower pump to operate. Second, the filter will plug rather rapidly requiring frequent backwashing possibly more than once a day. Back in the days when we had a swimming pool I remember that the amount of water to backwash the filter properly required quite a few gallons. You could redesign the system to use things such as bioballs, etc. but the inconvenience for access, the problems of rebuilding....I guess I'd use something else. You could put it out by the pond, take the top half off and use it as trickle tower (fill with loose, plastic straps or other biofilter media and let water flow over the top of the media and out the bottom of the unit back into the pond - if you want a nice, shiny art-object out by the pond. :-)
---David

I have wondered about the feasiblity of doing this as well. Aquadyne and Ultima-type filters look just like pool filters that have been adapted for lower-flowing biological filtration. Pentair pool filters and Pentair pond filters look like near-identical units (externally). As David suggested, one consideration is whether your pond pump will force enough water for effective backwashing. If your pump only delivers 1,000 gallons or so an hour, you might not be able to thoroughly flush such a system. If you try retrofitting your old pool filter, please post your results!

I agree with drh1, using a swimming pool filter isn't the best solution for most ponds with plants and/or fish... too much biological matter that can easily clog up sand-based filters.

I've been using an Ultima 6000 as my main filter (plus a solids filter, skimmer filter, waterfall filter and UV light) for the past 4 years and highly recommend the brand. My pond is 5000 gal and designed for "low" maintenance-- it takes me about 1/2 hour per month, two 15-minute sessions, to clean the mesh filters and backwash the Ultima. I use a PerformancePro pump (Artesian A 1\3-56) and it has more than enough pressure to backwash the filter. PerformancePro is another brand I recommend highly based on my personal experience as a koi-pond (not water garden) hobbyist.

Camperman,
Yes the outside container is a swimming pool filter but that is the only thing that is the same. Most use a DE multiport valve instead of a sand multiport valve so they can reverse the internal flow compared to a sand filter. Than the internal plumbing is totally different. A lot of bead filters use an air blower to help with the backwashing. The Ultima use to say that it required a minimum of a 3/4 hp high pressure pump to baskwash it properly. Can a swimming pool filter be used for a pond? Yes if you are willing to make the changes that are required but then it is probably cheaper just to buy one.
Mike

GARDEN POND ORNERS:I INSTALLED A SWIMMING POOL FILTER ON MY GARDEN POND.ALL OF THE SAND WAS REMOVED.RESEARCED INTERNET AND LOCATED SOME FORM TYPE FILTER MEDIA.THIS CAN BE CUT TO SIZE.MY NEW PUMP IS 5500 GPH.BUT HAVE USED A 2400 GPH THAT WORKED VERY WELL.DESIGNING AND CONNECTING THE PLUMBING I INSTALLED UNIONS IN THE LINES AT THE SELECTOR VALVE AT THE TOP OF THE FILTER.P.S. COURSE,MEDIUM.AND FINE.GOOD LUCK USE YOUR AMAGINATION. ALBERT

I have a old pool sand filter for my pond. I took the sand out, completely rinsed it out and refilled it with white strapping material like what they use at warehouses. Bought a roll from U-line for about 65$. packed about 1/3 of the the roll into it until I could fit no more. Before I turned this on my pond was ok but always cloudy, after I started the it up it took 3 days and I could see to the bottom of my pond with no problem (around 30"). I back flush every week because the skimmer brushes need cleaned and it is always transparent. BEST MOVE of my pond. Try it, sometimes pool people set them to the curb because the upgrade to a different filter. That's how mine came to be. I will find a pic and get it posted.

I have recently replaced my pool filter and pump. So I have a pump and filter available to anyone that wants to try this. I will trade for water plants. In MS

Hal can you post a link of the material you used?

sorry this took so long, here is what the filter material is.

https://www.uline.com/Product/Detail/S-1874/Poly-Strapping/Uline-Poly-Strapping-1-2-x-015-x-9000-White