Hello! I am chiming in with my experience with our painted pool. We bought our house in Dec 2011 and the 1970s pool was painted by the previous owner. Over the last two summers, our experience with the paint has been that it is definitely a Band-Aid and not a fix. I guess it would depend on what you want to accomplish as to if you want to paint or not. Are you just trying to hold off on doing a full replaster? Need to save up for a big project and looking for a short-term solution for now? I suspected our seller was doing just that, since the plaster under the paint is in pretty poor shape, but I did hear from our next door neighbor that it was an annual rite of spring for the seller to drain and repaint the pool... which makes me wonder, how much did he spend on paint during his ten year tenure?!
We are getting prices for a remodel now, and the plaster job is being bid at $9-10K. I don't know how much the pool paint job on our pool cost, but the same neighbor said when they painted their similar large pool it was something like $2000 (I don't know if that was DIY or not). I think they regret it now, as they already need to repaint or reapply and they moved in their house the year before we did. As a purely financial hypothetical (these are very ballpark figures), I would say if it costs $2000 to repaint or $10,000 to replaster, what is the cost/benefit? You could paint five times for the cost of the replaster, but you would have to drain five times, do the work five times, and deal with the headache five times, etc.
Now, we have not painted the pool each year like the seller because we plan to re-plaster. I know for sure it's been at least 18 months (since that's when we bought the house), probably more like at the minimum 24 months (since that was the summer prior) that it's been painted with the current coat. I can tell a difference in the fading of the paint color over the last two summers. It didn't look terrible last year, but this year the sun has faded the paint and in some areas it has started to look like there are roller streaks, where you might think they only did one coat and everywhere else maybe two coats (although I don't think that's what really happened, it's just the way the paint is wearing). This year, we do not want to brush the pool because as the previous poster said, it is "chalking," which seems to mean when we brush, a white cloud comes up and clouds the water until it settles/filters out again - that wasn't so evident last year though. However, last year we had a big problem with flaking plaster debris and chunks (with paint stuck to it) because painting the deteriorating plaster didn't make it solid, and as pieces come off, they get sucked up in the robot or the skimmer - we don't have a main drain so I'm not sure how badly it would infiltrate my filter if the robot wasn't able to get it up. This year I'm betting more of the loose chunks have already fallen because it hasn't been such a big problem, but the robot does pick up some paint chips and plaster chips with every vacuum.
The parts of the pool that had the plaster broken before painting do seem to be a magnet for algae spots - the paint doesn't seem to inhibit that much. And the parts that the paint has stayed on over the damaged plaster are still visible to me - thanks to TFP my water is amazingly clear and when the sun is coming up or going down, I can see every defect in the plaster surface. This is more obscured when the sun is high in the sky, though, without shadows being cast by the bumps and ridges.
That said, if we couldn't re-plaster soon, I might paint it again, but I don't think I would choose to be the one to initially paint a pool unless I just really had no other choice. I'm sorry, I don't know which paint was used in our pool. Our neighbor mentioned they had used some kind of epoxy pool paint, I think, probably from Leslie's. Good luck with whichever you decide!
PS - the painting of our pool means that the PB will need to chip out the plaster or sandblast the paint before it can be replastered. They said they sandblast in cool temps but chip out in hot (although it seems like I should prefer the chip-out any time of year, for longevity of my new surface, but I don't know).
