Solar Cover On or Off to Gain heat During the Day?

[Steve-D]

I have one of those thicker blue "bubble wrap" style solar covers trimmed to fit our in ground pool. With the flow of spring debris it has been easier to keep the pool clean with the cover off. Today the pool hit 66 degrees (whoo hoo!) and we're going into a stretch of 80+ & mid 70 degree days so this evening I put the cover on to try and retain what heat we've gotten so far (best day so far saw water temp hit 62).

My question is, if I want to maximize heat gain during the day should I leave the cover on or take it off for the direct sunlight?

 

[PoolStored]

You want the cover off when there is sunlight shining directly on the pool from reasonably high in the sky (ie not at dawn) and it is not too windy. The rest of the time it should be covered. The cover reduces heat absorption from sunlight, but there needs to be enough sunlight to make it worth a little evaporation, which is only when it is sunny and not too windy (which increases evaporation).

 

[Darin]

If you want the pool to heat up leave it on. During the day you will have increased heat transfer because the bubble cover absorbs the IR from sun and transfers it to the water. During the night it reduces heat loss by insulating the surface of the water from touching the night air. Also since there is not turbulence from the wind it reduces heat loss and evaporation during all hours.

 

[PoolStored]

If you want the pool to heat up leave it on. During the day you will have increased heat transfer because the bubble cover absorbs the IR from sun and transfers it to the water.

It is actually the opposite. If you have sun, high humidity and low winds, you want to take the cover off for heating during the day.

 

[sduda210]

I've heard that taking the cover off during the day will allow the sun to heat it faster but I always forget to put it back on. Then I lose all the extra heat and more than I gained during the day. To me it's better to just leave it on.

 

[mas985]

For most locations, and I have run the numbers on many, it is very rare that the wind and humidity are low enough where it makes sense to remove the cover during the day. I would just leave it on 24/7 until you swim.

Based on your location, you have both high winds and lower dew points which leads to very high evaporation.

Egg Harbor Township, NJ Weather History | Weather Underground

 

[Newdude]

You'd also have to have the pump off all day or you'd be making ripples on top of the wind.

 

[Steve-D]

Thank you all for the feedback.
The pool isn't in 100% sun until about 11 am so unless it's a hot weekend I wouldn't usually take the cover off until about then anyway. My wife likes to do her PT exercises in the pool at lunch when it's warm out so it all works out pretty well.

Otherwise, the cover usually stays on.

 

[Darin]

Cover on during the day then you will get warm water!! Have fun in your warm pool. My cover wore out and my water is in the upper 60's and will fall even more this week with cooler nite and day.

 

[Darin]

I've heard that taking the cover off during the day will allow the sun to heat it faster

This is actually backwards. The name is Solar Cover, it absorbs more IR from sun and transfers it to the water for greater temperature rise. The plastic bubbles are better at collecting heat than the water and liner.

Just take 2 buckets and fill them full with water in the morning. put a plastic bubble wrap on one and don't cover the other. place in full sun. then take the temperature at 4 pm. the covered will be noticeably higher.

Thus the name, Solar Cover.

 

[ngsm13]

You want the cover off when there is sunlight shining directly on the pool from reasonably high in the sky (ie not at dawn) and it is not too windy. The rest of the time it should be covered. The cover reduces heat absorption from sunlight, but there needs to be enough sunlight to make it worth a little evaporation, which is only when it is sunny and not too windy (which increases evaporation).

Hard disagree, as IR

It is actually the opposite. If you have sun, high humidity and low winds, you want to take the cover off for heating during the day.

Too many ifs. Real-life experience suggests otherwise.

I leave it on unless we're swimming, until middle of June. Then it's off for the summer as I don't like swimming in bathwater, lol.

 

[Newdude]

I didn't like taking it off to swim. Dealing with it to not swim ? Pfffffffft. Not a chance.