Stains on the cement under the pool cover

[Leesadesa2]

We have had inquiries asking why the concrete patio gets orangish stains in it under the area where the cover has been on after the pool has been covered over the winter. I can't be positive, but I believe that during the offseason in the northeast, the remaining chemicals in the pool can evaporate under the cover and the evaporated gasses can get trapped under the cover. The vapors can sometimes react with the concrete chemical compounds thus causing discoloration in areas where the cover is in contact with the concrete. Concrete can take several months to cure to 100% which would finally end the on-going chemical reaction of curing. Such discoloration is irreversible but it can blend in overtime due to exposure to the elements. We are researching with masons to see how to resolve this issue. I will update if we find any real answers or resolutions.

DOES ANYONE ELSE HAVE ANY IDEA WHY THE STAINS IN THE CEMENT HAPPEN BETWEEN THE POOL COVER AND THE CEMENT?

 

[ajw22]

What chemicals have you put in the pool that would evaporate and stain orange? Not chlorine or CYA or salt or maybe Polyquat 60. Those are the only chemicals used in TFP methods.

You have pics of the stained areas?

What manufacturer cover do you have?

 

[Kjp300]

Not sure what it is but I get the same stains. I know exactly what the OP is referring to. The stains fade as the summer summer rolls on but do not go away.

 

[1Sammy]

By golly i say the OP nailed it, 41 years and my cement deck still takes on a different color under the cover and straps..