Greg, I use the hydrogen peroxide to shock the pond every year before start up. I did that on March 17th this year. It brings up all the gunk from the bottom of the pond and gets rid of the algae from the season before. Then during the pond season I dose it daily at first during the cycling stage and then once a week during the rest of the pond season. It keeps it algae free even in the full sun and makes for a clear pond all season. This is a picture from this evening.
http://img.tapatalk.com/d/14/05/19/ra6u4uba.jpg

Very nice! Looks great.

Gorgeous! As usual :-)

Some of my pond plants are already a foot out of the water from being frozen all winter.
http://img.tapatalk.com/d/14/05/21/sy3a4ymu.jpg

Here you can see flower buds already coming up from my yellow pond lily.
http://img.tapatalk.com/d/14/05/21/ytanaryz.jpg

Like Kien has stated, the marsh marigold is always the first to bloom. Nice to see colour in the yard already.
http://img.tapatalk.com/d/14/05/21/y4u5uham.jpg

More lilies coming up. This is exactly 24" below the water surface - the deepest part of the pond.
http://img.tapatalk.com/d/14/05/21/y9urysyb.jpg

This is Clownie. The kids names him Clownie when we first got him years ago cause he's got memo colours. He has the most personality out of all the fish. Always one of the first at the food. Here, he's going out of the water just to try to get that one last piece of fish food in the corner.
http://img.tapatalk.com/d/14/05/21/jyqubabu.jpg

Very Nice
 

Wow! beautiful yard and pond, you probably mentioned this somewhere in your posts, just wondering if the fish come indoors in the winter?

They stay outside all winter. Most people that I've talked to that have tried wintering indoors and outdoors prefer leaving the fish outside. Keeping large fish indoors requires tons of water changes just to keep the water quality high. With wintering them indoors, you have to feed them which soils the water.

When I first started I used to winter my koi inside too. Did that for a couple of seasons until I couldn't take it anymore! You need a very large container, lots of water changes, etc. It was a royal pain in the butt. After doing more research and discovering that people overwintered their koi outside I went that approach as well and haven't looked back. Any ya, it always surprises people whenever I tell them that the fish stay outside all winter. Genetically koi are a cold water fish. They will hibernate just like any other lake fish.

How do you keep the pond from freezing solid during the long Edmonton winters? I lived in the Cold Lake area for many years and the lake ice would be several feet thick! Seems to me your 24" depth could easily freeze all the way down during a cold snap? Even though the koi hibernate as Kien mentions, don't they still need O2, especially considering the size of some of those bad boys?

Do what I do....disconnect the waterfall pump and point the outlet straight up. 4280gph shooting to the top keeps a nice sized hole open.