Can evaporation occur with autocover closed?

[mmesqc1578]

If keep autocover closed at night, can evaporation still occur? Lost about 1/8 inch in 18 hours. 3 of the hours the cover was open. Water is kept warm 80 degrees and night temps here are in 50s.

 

[Mike1162]

How'd to happen to notice just 1/8 inch? I'm sure you wouldn't lose it through a closed cover. With that difference in temps you'd get a lot of condensation on the bottom of the cover. Some of that condensation would roll up with the cover but probably 1/64" or less.

 

[mknauss]

Unless the cover is hermetically sealed, there will be 'some' evaporation. Very small however.

 

[JoyfulNoise]

That's a huge temperature differential. There is a very large driving force for evaporative loss. Any exposed pool water will want to evaporate at that temp. 1/8" is really small so I'm not too surprised

 

[mmesqc1578]

How'd to happen to notice just 1/8 inch? I'm sure you wouldn't lose it through a closed cover. With that difference in temps you'd get a lot of condensation on the bottom of the cover. Some of that condensation would roll up with the cover but probably 1/64" or less.

I marked water level with piece of tape at skimmer.