Are those links supposed to be showing rock pools with problems? All I am seeing is just pictures of beautiful pools with rocks.
No, sorry, confusing. I was contradicting myself (on purpose), wanting to be fair. I googled for the type of pool the OP was looking for, and found plenty. The OP mentioned that they didn't find much in the way of that type of pool on TFP, and I quipped "Maybe cause they don't work." but obviously they are out there and somebody knows how to build them, and lots of folks (some number, anyway) have them. And I agree, some of them are amazing looking. I think some can get a bit gaudy, when they're overdone, or are in a setting or yard that doesn't support the look and structure, but others look very close to a natural element, they look as little like a swimming pool as possible and more like a pond, and those are very cool.
Again, don't mean to come off like "No way. You can't/shouldn't do that!" but rather "Just know what you're getting in to." Not that I
know that (never having had a pool like that). You're more the expert than the rest of us nay-sayers...
I'm projecting and I'm lazy. So my point of view is skewed. I don't want to make things any harder on myself than necessary, so wouldn't want a pool like that. Not being able to walk all the way around it, to enjoy that aspect, or to maintain it, is not for me. But if the OP is willing to trade off the potential maintenance tasks and risks for the payoff of that type of pool... coolio!
We teach/preach here that if you maintain TFP guidelines you'll never have algae. And up to a few months ago I was the head cheer leader for that premise. Perfect water since day one, not a hint of algae. TFP rocks! But I got into a hot week and had a big swim party and then got a little careless and my FC just
barely dipped below my minimum FC. For about a day maybe. Boom. Algae! (Which actually
proves the premise!) I didn't have to slam. If was just a tinge on one section of wall (the one that gets the sun). I goosed the FC a few points and brushed and brushed and I haven't seen it since. CC is 0. I think I got away with it. But had that been a rock wall, the brushing wouldn't have worked and that little bout could have turned into a full-blown bloom. So that's where I'm coming from. If the OP maintains perfect TFP water, then maybe they'll never have an algae problem, but if they slip, their algae problem could get uglier than it would in a "non-rock" pool. The efflorescence issue is separate. I'm starting to see it now in my pool. My CH is dead on for my pool, I'm compulsive about CH, but I'm getting a tinge of efflorescence anyway. I believe that to be from evaporation, and not a CH maintenance issue, and seems to be inevitable in my pool (The previous owners let it get out of control. Took bead blasting to get it off.). So I do think that's a real issue for rock near the water. But again, you have more experience than I with the rock and efflorescence.
Just opining, take it or leave it.