Do not acid wash your pool! It will force your hand for a re-plaster, and just put money in the pocket of the guy that does the acid wash. I will always refuse to do an acid wash, as I know what it will do to plaster!
Save your money. It will destroy your finish and you will not be happy!
There are two things going on here. One, in very hot areas you don't want to drain the pool while it is hot and sunny in the summer because high temperatures without water can cause the plaster to crack. If the weather is mild you can drain for a couple of days, but don't drain when it is really hot.
The other is acid washing. Acid washing will significantly affect the lifetime of the plaster, but sometimes not acid washing is worse. It all depends on why you think you need to acid wash and if, or how many times, the surface has been acid washed before.