Sorry, Surface Bonding Cement such as Quikwall by Quikrete.
For free standing walls sure. For the kind of stress a pond sees this would be a complete waste of time.
I figured if I could get the pour done in February there wasn't much point in filling the pond right away. Why not let it settle for the time and deal with any cracks before I line it?
I think I understand now, you're thinking the concrete is just a structure, not meant to be water tight. To me there's 2 basic ways to build a pond, or swimming pool for that matter.
First is a structure, even if just a hole in the ground, with a rubber liner. Same for inground vinyl pools. The structure can bend, crack, move, etc. with no impact on the liner's ability to hold water. The structure just has to be strong enough to not completely fail.
Second, a cement pool or pond is a different deal, they're built to never crack, ever. They only crack when poorly built. Today this is mostly the sprayed concrete (gunite) but some do still do pour type builds with forms which is what you're thinking of doing.
Normally a cement pool/pond requires a couple of coats of material bonded to previous layers. Letting the structure sit for months adds dirt which reduces bonding or requires a lot of cleaning. Just adds risks. Some products also require a new surface for bonding. There are ways to create a "new" surface again, but more work, more risk. With no up side.
I am currently thinking polyurea although I am open to suggestions regarding its durability, cost, etc.
I've never used it but it seems like a great product. There is one thing you have to be careful about. Most people read it stretches 500% and think that will deal with cracks. But that isn't as good as it sounds. The product adheres to the concrete. A crack starts almost infinitely small and gets wider. Because the polyurea is adhered to either side of the crack only a thin bit of polyurea actually stretches. So even a 1/16" crack could exceed the 500%. Great for hair line cracks. And that's why the concrete structure is built the same whether polyurea or a plaster finish.
A liner is much different. Not attached the underlining structure can crack, move and deform a lot and the liner will still function.
Is it OK to keep posting here as well?
Absolutely. It would be a very cool pond build to see and I'm sure would be very popular. I just wanted to point to you a resource.
The pond we are going for is sort of in-between.
That is the main rub I think. If you're building a Water Garden there are lots of people here with that experience. If you're building a Koi pond there are lots of people on Koiphen that can help. The inbetween is tougher because so few people do this. Even mentioning Goldfish in Koiphen can sometimes get some not so funny ribbing. Both camps will assume you're building their kind of pond and the advice can then be all over the place.
However, this type of pond is very common in the far east and they do have English forums. It's a little tricky because they have different product names and building methods.
I don't know if you're at all concerned with resale value but an inbetween pond can have issues. If you're going to spend $20-30K I think it'd be worth the extra $10k and build a proper Koi pond. It would be more attractive to buyers looking for a Koi pond. And if you get the bug and later want more Koi you won't have to rip out and rebuild. Or just build a Water Garden which is perfect for Goldfish and a few Koi. Way less stress and a lot less money. You can still spend a lot on finishes, lighting, and plants.
) I'm thinking solid block, cut to fit, drilled top and bottom for rebar pins (epoxied in) and grooved with a grinder for the horizontal rebar (epoxied again).