Saltwater Garden Ponds: Is it possible?

Hippocampus kuda

Reefing newb
I always wondered if saltwater ponds are possible. I mean, if freshwater ponds are possible, how 'bout seawater? And instead of freshwater plants, why not sea grass or robust corals that would survive extreme water changes? And instead of kois or catfish, why not marine fishes that would tolerate large amount of water changes? :-? Well there might be some problems with the idea when it comes to temperature change (especially when winter comes), water chemistry (rain pouring down unto the pond), and especially, choosing the right fishes and corals/plants that wouldn't die when bad things happen. But despite all of these, is it really possible to construct a saltwater pond in your backyard? I need answers, please! :D

(Sorry for any grammatical errors or mistakes that I have written :/ as you can see, I'm a Filipino__which means I come from the Philippines__and most of us here don't know how to speak or write english properly, or in some cases, don't know how to speak or write english at all. And I am 13 years old and I'm trying my best not to write down any grammatical errors). :P :D :)
Its possible but difficult. There would be many problems: A small shallow pond could easily over heat in the climate of the Phillipines. If you use cement to make the pond floor the alk will be sky high until it finishes curing.

In Thailand they breed clowns in large cement tanks. They have so many that they have to throw a thousand into the sea each month. They prevent heating and chemistry problems by pumping seawater into and out the tanks fast enough that the seawater can't cool or over heat and well before it can change chemistry.