Pond Planning - Advice Wanted

[pisanoal]

Hello All,

5 or so years ago, i bought a house that had a koi pond already, and although i made some significant upgrades to that pond i was always limited by the original design (no bottom drain/no good way to add one, size, no built in skimmer, limited space for filtration components). We recently moved and I want to install a new pond, and do it right the first time. Main Goals: big enough to not want to upgrade (3-5k gallons), as easy and hands free as reasonably possible, budget friendly. Obviously those are probably things that everyone wants, but i just want to be especially mindful of all of those points when making design decisions.

With that being said, to get it started, here are my thoughts on main design features:

Size-shape: Rectangular Pond - 10'x18' 4' deep (5,400 gallons)
Build-Type: In-ground liner pond with one course of cinder blocks above ground (to keep runoff out and provide a "bench" all the way around the pond) - the liner will wrap over the blocks.
Filtration:
Aerated Bottom Drain (3" or 4") - bottom will be sloped towards the BD to help reduce the need for a second BD. BD circuit will route to main filtration.
Skimmer - Leaning towards a separate circuit with TPRs to again help with BD collection. Ability to route to main filtration if BD circuit goes down. Thoughts on tying this in to the BD circuit? (from a cost and ease of install perspective)
Main filtration:
RDF - first filtration component, pump fed. My thoughts are to go from the BD to an inline strainer-pump. The pump will be placed just below ground level to be self-priming/quiet. Can I run the BD line to the wall of the pond, then 90 up to the
pump? Or do I need a more gradual slope? Also would like discussion on building in the potential to add a sieve or other pre-filter before pump.
Anoxic filter - my thought is to build a small upper pond with some anoxic filter baskets for nitrification/denitrification with a waterfall return. Gravity fed from RDF
Ability to add a fines filter down the road if necessary (between RDF and anoxic filter).

[*Ci*]

Your plan sounds pretty good. A couple of thoughts:
A 90 on the bottom drain is do-able, a gradual incline or even just a sweep 90 would be better as far as the total head is concerned.
if you are incorporating an rdf right from the start, I do not think you will need to add a sieve in the future, unless you add it to a separate skimmer circuit. I would not tie the BD and skimmer together, just send them both to two different inlets on the rdf. You could do both of those gravity fed and have the pump after the rdf.
I think an rdf would be sufficient pre-filtration for an anoxic filter. I think you could gravity feed bd/skimmer —- rdf—-anoxic pond —- then pump to a pair of s&g for fines —- waterfall return (or a combo waterfall & tprs.), but I could be wrong about that. Someone with more rdf experience will hopefully contribute their opinion.
Got any photos of the new pond site?

[KingstonKoi]

As someone who bought a house with a smaller pond, your stated goal of "big enough to not want to upgrade (3-5k gallons), as easy and hands free as reasonably possible, budget friendly" are wonderful. Easier to do from scratch than a remodel, but the one that especially resonates is"big enough to not want to upgrade (3-5k gallons)." Please keep us posted on how things go during the planning, build-out and new pond stages.

[pisanoal]

Thanks for the input. I especially appreciate the feedback on the sieve.

The sweep 90 is probably the way I will go due to the ground being incredibly hard here. The less digging, the better. I would gravity feed, but that goes back to least amount of digging/ease of maintenance. I know it would be better to gravity feed as far as fines/etc, but I think I'd rather build a couple fines filters.

I'll post some photos of the pond site tomorrow. I don't have any handy.

[pisanoal]

I'll definitely keep this thread updated. It will be several months before the start of the build. We just put up a large shop and did a bunch of dirt work around it, so we have to build up the cash reserves again before buying koi pond equipment

I want to have everything laid out so I know how much we need to budget for.

[Kathy]

Ci's post above is how I'd go escept I wouldn't be concerned about the fines filtration. We have a 5000 gal turtle pond with 2 BDs and skimmer on separate lines that gravity feed into a rdf that gravity feeds into a 700 gal anoxic filter with 70 baskets then pumped back to the pond via waterfalls and a tpr. I wish we had added one or two more tprs being that our pond is circular. This setup keeps the water clear. That being said, our anoxic filter is set up where debri can collect on the bottom and be drained out through cleanouts. Good luck to you!

[nrpdyer]

What jumped out to me is that you want a 5,400 gallon pond with one bottom drain. Your going to need to consider how much turnover you want on this pond and how that water is going from the pond to the filter. Do you want to turn the volume of the pond over though the filter once per hour? twice per hour? Unless you have considered this in your skimmer / tpr setup somehow (I don't have enough detail on what your thinking), you will be pushing 5,400 / 10,800 gallons per hour through one bottom drain line? Just for reference, I am pushing about 8,000 GPH through two 4" lines from my bottom drains and a 3" line from my skimmer. This leaves me with about 1.5" of level difference between my pond and my RDF when operating. I also built my pond with a 3" mid water pickup in case I had problems with the level differential. I haven't had to use the mid water pickup though. Of course, the length of plumbing, number of bends etc will affect your level differential but I can say for certain, one 4" line will not do to carry that volume (again, maybe you considered this elsewhere). This advice is more for gravity fed but still, consider your restrictions for that volume flow...

As for 90 degree riser from BD to filters, I never figured why everyone did that but to save a little digging. I did two 45's and angled mine up; quite happy with that (but I don't have anything other to compare it to) and just 'figure' maybe debris can be carried up the sloped pipe easier than straight up (I know this could be a contentious point too as it still has to rise up the same height; haven't fully thought through that one).

[two_wheeled]

Your needs sound exactly like mine about 8 years ago. I had a small "aquascape"-style pond (it was pretty, but not ideal) that was destroyed twice by raccoons, which started me down a path of education and several years of planning to create my new pond.
What I ended up is a 3000 gallon pond, rectangle, 2 feet above ground and 2 feet below. Cement blocks with rubber liner. I hid all of the plumbing and placed my filters about 20 feet away and out of sight. I have one 3" skimmer line and one 4" aerated bottom drain with a very gentle slope on the pond bottom that helps the waste naturally go out to the filters. In 5 years, I have NEVER had to clean or vacuum the inside of the pond. I'm extremely happy with this setup.

My intention with this post is to say that I think you're definitely on the right track! I like your idea of using bottom drain(s) with a sloped bottom, but I would add that only a very slight angle is needed for waste to naturally go to the drain. The water flow from BD aeration will help with that too. No need to overdo that slope.

[pisanoal]

Ci's post above is how I'd go escept I wouldn't be concerned about the fines filtration. We have a 5000 gal turtle pond with 2 BDs and skimmer on separate lines that gravity feed into a rdf that gravity feeds into a 700 gal anoxic filter with 70 baskets then pumped back to the pond via waterfalls and a tpr. I wish we had added one or two more tprs being that our pond is circular. This setup keeps the water clear. That being said, our anoxic filter is set up where debri can collect on the bottom and be drained out through cleanouts. Good luck to you!

I like the idea of having cleanouts in the anoxic filter. Definitely going to steal that idea!