You would be surprised what a professional pool cleaning Co could do with those tiles. I believe they use a pumice? stone to clean the deposits. They also sell quite a few chemical cleaners that work well. You would also be surprised at availability of old pool tile especially in a central area.

PLEASE do not follow the current trend on TV to do a half assed job just to trick and sell your house. Don't forget someone actually has to live there and not everyone has the ability to pay to correct half done cover up work.

i'd add a few solar powered lights to the landscaping and include a night photo for your listing.