Outdoor temperate salt pond!

[Garden sharks]

Hi everyone -

New to the forum, and I have a TON of questions. But before I get to them, let me preface with a bit of my background -

I own and operate a small marine import/wholesale company in the Midwest, focusing primarily on less-common collected animals (NOT rare/endangered/threatened!) purely as a hobby, and also spend a considerable amount of time and money on my own captive breeding programs for different exotic fish and invertebrates. I have a background in marine biology and would consider myself to be a so-called "advanced aquarist". I'm only mentioning this before my questions because I am used to a lot of unnecessary ad hominem attacks when I want to try something new or different.

Now, to my pond.

I have several Urobatis halleri (a small, friendly sting ray collected in California) and a juvenile pair of Heterodontus francisci (known as horn sharks, also collected in California). These are pets and are hand fed and played with daily; the rays have been breeding successfully for a couple years as well.

I am toying with the idea of building an outdoor pond for them but have some logistics issues I need to solve.

My basic idea is:

1. Build the frame as a standard plywood/fiberglass tank,
2. Submerge the tank to extend below the freeze line - local pond people tell me at least 2' into the ground. So tank dimensions would be roughly 10'x10'x5' - depending on how deep I need to go. I'd like it to be at least 2-3' above ground so I can put in a viewing window on one side
3. Have the "sump" in my basement, plumbing the return lines and overflow through a basement window and having a large volume of water there for all the filtration equipment to. I'm a fan of automation so filtration will primarily be fleece roller mats, algae turf scrubbers and a large fluidized sand reactor. I'll probably need other media reactors (purigen, etc) as well but with scrubbers and fleece I'm running nearly 0 no3/po4 levels in large heavily stocked systems.

So my first set of concerns:

1. Waterproofing the exterior of the tank. I had this idea to line the hole with benonite clay before building, and then filling in/packing the sides to prevent moisture from getting in. A friend simplified it and suggested to just use roofing tar, tar paper etc. for a guaranteed seal, but I am open to ideas

2. I could really use help planning depth, temperature etc. I live in zone 6a and I have a lot of concern about maintaining 55 - 80f year round. Cooling is easy in the summer as I can just add a large titanium based chiller to my existing AC (intentionally oversized for this), but heating in the winter is a concern.

I assume I'll need to add a number of titanium heat pumps. I was looking at the "electro" pumps, but I am confused on how many I should plan to use.

Assuming the system ends up being 4200 gallons or so (500+ in the basement), I will be running at least 5x Sicce Synchra 16 (4200gph pumps). Do I want to to with smaller pumps and go 1:1 with the inline heaters? If so, help me with the math so I can figure out how many are needed to keep the temperature stable.

I should add that I will probably cover it for winter as well, to prevent evaporation and not as a thermal barrier.

3. Things I'm not really concerned about - salinity swings in rainfall, environmental contamination (pollen, leaves other debris).

Really just temperature and waterproofing right now.

Thank you!

 

[j.w]

@Garden sharks
I could never even begin to help you w/your build, just saying hello and would be neat to see photo's of your setups!

 

[Mmathis]

Hello and welcome!

I’m with @j.w. I don’t have a clue.

 

[Lin]

WOW! Welcome. Pics, please.

 

[poconojoe]

You are well above me on the knowledge scale.

Have you considered using an EPDM liner? That is what most of us use. It's usually laid on top of a specific underlayment for that purpose. You buy them together.

As far as keeping that water at a tropical temperature in zone 6a, I guess you'll have to have a heater that is up to the task. There are some here that cover their ponds for the Winter, but I don't think many heat their ponds. Some have built structures over their ponds for the Winter, sort of greenhouses.

Keep us posted and throw up some pictures as you progress. This will certainly be an interesting build.

 

[Ronfire]

I would think of building a seasonal greenhouse if you plan to heat in the winter. I would look at a liner for the pond but place rigid insulation behind the liner to help with the heat in the cold season. You could also cover part of the pond with the rigid insulation for the winter.

 

[Mmathis]

After reading this a second time, I’m wondering if we are the best choice of a forum to help you with this. Our area of expertise is garden ponds. It almost sounds like you need to be discussing this with an exotics group, or even a forum geared more toward the particular animals you are wanting to house.