I installed a 900+ gallon pond 4 weeks back. Stocked it with plants and then fish (light load). Laguna filter with UV, bubbler, etc.

I then built a deck next to the pond. It overhangs it on one side by 6 inches or so. I used pressure treated lumber. All was fine for a few weeks... then we had a rain that lasted all day. A few days after that, all of the oxygenators died all in one day. The floating hyacenth and lettuce are hanging on barely.. yellowing out.

LESSON 1- So knowing that the copper treatment leached out from the rain, and causing many issues.. i have been doing water changes frequently. Though the copper does of course keep the algae down completely...

QUESTION 1- What should i do to remove the copper? Can i filter it out? Charcoal filter?

QUESTION 2- I want to create a spill over waterfall of some sort from the return water from the filter. I want to do a "rill" where it makes that nice sheet of water spilling over. I was planning on using the Pressure treated lumber to make the form, and then line the inside with something that is inert (as possible).

I have the option of using Galvanized Metal? Does this corrode or effect water quality? Or should i go with stainless steel?

Any help would be great.