There's one in El Salvador 5470 (between Juan B Justo and Humboldt).
I use it all the time. but it's close for renovations till monday 29th.
It's pricey, relatively speaking but it's basically a good pool for lane swimming.
Open air in summer too.
in every country I've been in, what payment entitles you to differs. Can you turn up when you want or do they give you time slots or is there some odd hybrid of all that?? And can you stay as long as you want or do you get hooked out after an hour?