Greetings. I'm building a new pond soon and would like some advice and recommendations from wiser people than myself. I intend to build a partial above ground pond that will be approximately 5 feet deep below surface and maybe 2 feet above surface. The above ground will be some type of cinder blocks or capstones and it will be lined with a Firestone liner. The water parimeter will be 10x16'. I calculate it will be close to 8500 gallons. Here's what I'd like to do, and I'd like everyone's input on my build, where I'm wrong, and what I could do differently to maximize filtration and flow:
First off, I have ZERO desire to do a gravity system with a pit, and want to use a SMF10000 EasyPro Skid Mount Filtration System that's rated at 10000 gallons and pump is rated at 7800gph. It has a bead filter, UV, and pump. I'll try to attach a picture. I'd like that pre-plumbed system to be at ground level right beside the pond in the middle of the long axis (where I intend for a waterfall shelf to be located). I'd like to have 2-3 bottom drains, 2 or 4 returns that are just a plain PVC pipe somewhere in the sides of the pond, and a main return to a simple 24 or 36" shelf-like waterfall (no rocks and such. just a simple overflowing shelf out of the above ground retaining wall). No plans for a skimmer. So here are my main questions which all about plumbing to maintain proper pressure/filtration/flow.
1. The pre-plumbed Easy Pro system I'm buying has 2" inlets and outlets. What size PVC (2",3", or 4") should I use for the drains? I've heard that you should use 4" drains with gravity systems and 3" for pressure systems. HOWEVER, this system (and most others) has 2" inlets/outlets... so what good does it do to upsize to 3" lines/drains if I'm already bottlenecked to 2" inlets? (FYI - I'm fairly capable at building, but not real savvy with the water dynamics).
2. What size returns should I run back to the pond? probably just 2"?
3. Any recommendations on placement of the returns? Deep? Shallow? At the edge? Near the center? Alligned vertically in one corner? Alligned horizontally at the bottom? I ask because I want it to HELP the water circulation/drains and not hurt it.
4. What parts do I need to seal the liner around those 2" returns (similar to a collar on a bottom drain I assume)?
5. Where all do I need check valves and other "special" plumbing pieces if the pump/filter are above ground/drains but technically below the surface of the water level since it will be partially above ground?
6. If I have multiple drains, should I connect them together with a single return pipe? Or should I have a return pipe for each drain? I can see the advantage of having return pipes for each, however, that increases the amount of head. Is it too much for the pump or no big deal? See question 1 again about what size returns lines/drains I should use.
7. I'm thinking 2 drains cause that would have each catching a 5' radius area if the pond is 10x16.
8. On YouTube, I've seen a ton of ponds built simply with 16x8x4 "capstones" instead of true cinder blocks. This is what I'd prefer, but I sincerely don't understand how this is as stable as cinder blocks with internal rebar. But for my purposes, it would only be supporting maybe 2' of water.
Any other thoughts are GREATLY appreciated, so long as it isn't "you need to do a gravity system", "you're doing it all wrong", or "You need a skimmer to do this right". This needs to be a simple clean build for me which is why I want a pre-plumbed filter/pump system.
THANK YOU, THANK YOU, THANK YOU!!!