Koi pulled up all of my water lilies in that pond last year. I'm still scheming what to do about that. I don't have any trouble with filamentous algae in ponds like this one, either because of algal competition or because the koi don't let it get established, but I do have to clean it out of my unfiltered lotus ponds a couple times a year (just did that a few days ago on the big lotus near this pond).
I've had the goldfish multiply in the my ponds, but not the koi so far. I don't think I've done a good job of giving them places to breed, but like you, I'm not sure what I do with the babies if they did have them.
I'm hoping this forum will pick up a bit as the weather warms in the northern hemisphere. I suppose the Garden Association changes will eventually expose us to more people, but the great members already here have a lot of good stuff to share when the weather warms up.
