Hi all I'm looking for some help for one of my clients who has a 3 tiered 3000 gallon pond system that the previous owner had custom built for a really nice koi pond, but my client the current home owner is having a tuff time keeping the algae under control we live in az and at some point the temp out side will get below freezing so around 27 degrees in the lowest point of the night in winter and he seems to be inexperienced in ponds or fish keeping for that matter. I take care of his pool and we were talking and I figured since we both share some level of "love" for the same hobby and wanna help him out any one have any idea of a algae eater that can handle freezing water temps in the winter and warm water in the summer. Or what is a easy solution that you lucky pond people use to take care of algae that won't harm the koi in there now