My pond is approx 500 gallons. In past years my pond has quickly turned green and brown. This year I am determined to get it right. My pond has been neglected for 2 years (no fish) and is currently completely full of leaves and water. Im going to COMPLETELY empty it and start over. Im wanting to order a new filter and pump (all in one unit with fountain). I found one from The Pond Guy. It has a mechanical and biological filter as well as uv. Do i need to add beneficial bacteria when i start it back up? I plan on buying a bunch of plants and eventually adding goldfish. Basically, how do i get things started without getting new pond syndrome?