White spots on stamped concrete after winter

I've tried searching for my exact issue, along with other information, but can't really find a suitable match.



Last fall, I re-sealed my then two year old stamped concrete patio using a water based sealer (Anvil Ultraseal 1330, per Anvil's suggestion); I used this after a lot of searching, since I was unable to find out which sealer was originally replied because the company was sold to another individual. I re-sealed doing the following:

• Power washed the entire patio


• Used Simple Green degreaser and scrubbed the entire patio


• Waited an entire week, which was completely dry and in the 70s-80s


• Sealed the patio using the above sealer in three light coats (with a roller brush), allowing the proper drying time in between coats

Initially, the results looked okay. I noticed some spots were a little darker than others, but figured that would resolve itself in time. Fast forward a few months to winter, which was pretty bad this year (East PA). I started noticing white spots all over the patio, which I assumed was moisture. Now that the snow is gone, the patio looks horrible. There are white spots everywhere.



At this point, I have no idea where to start. Should I be stripping off the old water based sealer and then resealing with something else? How, and which sealer? Some sites say I can just power wash the old water based sealer off, and then reseal with water or acrylic based sealers. Others say I need to use a chemical stripper first to get everything off the surface.



Any chance somebody can provide some in-depth advice on what I should be doing here? I can take pictures when I get home if that'd help, and thanks in advance.

White spots on stamped concrete after winter