hello rimix,

Your PB is absolutely correct. What you are seeing is a white calcium hydroxide precipitate resulting from the reaction taking place in the cementitious products. The fact that it has rained alot bodes well for the structure as it cures. The more you wet the concrete, the more it reacts, the more calcium hydroxide precipitate you will see, the higher the PSI will be until fully cured. All swimming pool shells are leaky in the absence of waterproofing. Waterproofing does add cost to your project but the benefits may be worthwhile for many reasons and you should explore that with your builder. Now the issues with the tile are no different. The tile sits on a cementitious mortar bed and is surrounded by a cementitous grout all subject to the same reactions. Many homeowners have had concrete pools built without waterproofing and just manage the maintenance issues that present as a result of this reactivity which is beyond the pool builders control. You have decide what is tolerable and acceptable for yourself but I do not see anything here that indicates anything other than the fact that your PB is knowledgeable in his assessment.

Thank you diypoolpro! I had no doubt that my PB was being straight with me, but I couldn't find anyone else having this issue, so it worried me a little. We are going to discuss waterproofing with our PB today when we meet about plaster colors. Here is a picture of the calcium deposits.

Here is a link that might be useful: