Really nice job! I'll post some pictures of my Koi pond this week as well. Our pond was originally setup with a built in 2 HP pump with a sand filter. After having trouble trying to keep the water clean, and the filter from constantly clogging up, I decided to remove the sand and replace it with bio media. I started leaving the filter on 24/7, and my electric bill sky rocketed! Also, I was still having trouble trying to maintain a clean pond.
Earlier this year I purchased one of these:
http://www.webbsonline.com/Item/R440021?gclid=CKCn8ZLW6r8CFcI7MgodeEIAqA
It's an all in one pond filter, with a built in UV light. The UV light has really made a huge difference, no more algae! The water finally remains crystal clear. Not sure if you have a UV filter, but if not, definitely get one. You can go to Lowes and buy just a UV filter for like $20, and it will keep your water clear (however you still need to filter out the particles). The all in one consumes very little power, and I haven't noticed any change in my electric bill. Some of these Koi companies will tell you that you have to spend literally thousands of dollars on a filtration system, that's complete BS. You can make your own system for just a few hundred dollars, or simply buy an all in one unit. The unit I have filters I believe up to 2500 gallons.
Unfortunately I lost about 15 fish recently to a Blue Heron. I caught the damn thing several times trying to eat my fish. It stands close to 5 feet tall! Anyway, it puts its big beak in the water, and scoops up the fish. I ended up buying some bird netting to put over the pond, which has since kept the Heron away.
I just looked at the picture closer, and it looks like you built your own filtration system. What are you using?