Evaporation

[tcat]

I noticed last night I got more evaporation than I did during the day yesterday (no cover). Pool is shaded, but got about 25% of 80 degree sun. Was 50 last night, pool at 87 (now 82). Went down 1/16" yesterday, 1/8" last night. It's this normal? Does not go down with cover, so no leaks. Lots of steam at night, so I'm guessing the temp difference is causing the excess evaporation. Time to start using the cover again.

Sent from my Nexus 6P using Tapatalk

 

[Richard320]

Wind seems to make more difference than temperature in my experience.

 

[JoyfulNoise]

It make sense you would lose it at night. Generally speaking the pool water temp will lag the air temp during the day and evaporation will be minimal. Once the air temp drops (and if the RH is low), the pool water will be much warmer than the air. Once the watt temp is even just a few degrees above the air temperature, evaporation rates will increase.

It is better to keep the pool covered at night to reduce evaporative loss.

 

[tcat]

Makes sense. Glad it wasn't windy! Funny, thought since day temps were above 80 I could start leaving cover off, but nights are still 40s and 50s. Losing an inch of water a week is 800-1000 gallons per month. Makes the labor of adding the cover easier!

Sent from my Nexus 6P using Tapatalk

 

[mas985]

The evaporation rate is dependent on the difference between the water temperature and the dew point temperature (air temp + humidity). So if the dew point temperature dropped at night, then evaporation would increase. However, air temperature can drop without the dew point temperature dropping and in that case, the evaporation rate would not change.

 

[DaninFLA]

humidity and wind are big components of evaporation. it can be hot and very humid and you can lose less water than on a dry/windy day

 

[kywildcats]

Wind been blowing hard here all week, and I've noticed more water loss than usual.