I have a pool deck that another contractor poured and the homeowner is wanting me to fix and seal the pool deck. The deck is stamped and sealed. When it was resealed after the initial sealing which was approx. 1 1/2 yrs white spots appeared under the sealer. This is a salt water pool and it appears to be worse in the areas that get a lot of sun light, the shaded areas look fine. I used xylene on a test area and it doesnt seem to have helped it any. I was told to used a xylene and MEK mixture on it which i havent done yet. Im wondering if anyone else has seen this before and how you fixed it. I can email pics.