Clear solar cover or full sun?

[KarenNJ]

We just got a clear solar cover. We have always used the blue ones and I take them off during the day because the full sun heats the pool way faster than the blue cover. This year we got a clear one and now I am not sure if I should leave the cover on to heat up the water or open it up for full sun? Outdoor temps are around 70 f with full sun.

 

[mas985]

Have you actually experimented with either the blue or clear covers on vs off? The color shouldn't matter that much. A clear cover is not that much more transparent to solar radiation than is the blue cover. Both have about 80% transmissivity. So unless you have very high humidity (i.e. low evaporation), having the covers on during the day (and night) should result in higher water temperatures.

 

[kevinskii]

That's surprising, my experience is that the pool heats up much faster with the blue cover on than off. This morning in southern CA it was in the low 70s, and the pool went from about 82F to 85F in a couple of hours. It has gone up 1 degree in the couple of hours since I took the cover off, even thought it is around 80F now and there is no wind.

 

[KarenNJ]

hmmm, I always felt it heated much faster sitting in full sun. I need to get three small pools and blue, clear and nothing and do an experiment! I guess I will leave the clear cover on for now.

 

[AndyTN]

Look at your dew point compared to air temp to see how much of a difference there is. If there is a small difference, you won't have much evaporation. Assuming your pool water is close to the air temp in the afternoon, if the dew point is low compared to the air temp, you will have a lot of evaporation. Wind is also a factor which will cause more evaporation.

You will get more solar radiation into the water without the solar cover but if the dew point is a decent amount below your pool and air temp, you will be losing more heat due to evaporation than you will gain by not having the cover blocking a little amount of sun light.