I did a lot of research online and came across what's known as a "Skippy Filter". Basically you pump water from the pond into a bucket all the way to the bottom. The bucket is full of some sort of media with lots of surface area like lava rock or scouring pads. Near the top there is a hole in the bucket so that the water level stays in the same place. As the water fills the bucket from the bottom up the water is forced through the filtration media and flows out of the overflow hole near the top.
|water is forced to the bottom|
through the pvc
On top of the lava rock that I used as the filter media, I put in some expanded clay grow rocks to support some plants. I've got sweet potato, pineapple basil, and a sweet potato that I started indoors now growing in the top of the skippy filter. So far so good.
In due course I will add a charge controller to recharge a deep cycle battery that can run the pump 24/7. The pump draw is miniscule so I might be able to run some lighting as well. We'll see.