Waterproofing Wood Around the Pond

[jhenkel]

Shalom, I'd like to waterproof my waterwheel this fall after it gets well weathered; does anyone have nay experience or recommention for a wood preservative product??

I understand most preservatives have copper sulfate and that copper is very toxic to Koi, so I'm a bit nervous.

Then like to use a marine poly as a top coat?

Tanx,
McKool