In your case, the sand filter will suit you very well. You will be doing a lot of backwashing when you bring the water in and sand is best suited for that.
What worked for me was to pump the water uphill from my pond using the irrigation pump and push it directly into the pool filter.........then, from the filter, directly into the pool using the existing pool plumbing.
Then, once the pool was filled, I disconnected the irrigation pump from the filter and hooked up the pool pump to the system.
I probably backwashed about every couple of hours as the junk from the pond was caught by the filter. The water in the pool was still greenish and loaded with algae but most of the larger stuff had been filtered out.
Next, it was simply a matter of starting the pool pump and massive doses of chlorine (read "How to Shock Your Pool" up in Pool School) for about 3 days or so and I was done.
Your pond water may be cleaner than mine but I don't think I would've had much luck with DE or cartridge filters......I think they would've clogged up a lot more often.