My old blue one which is gone now, used to have about 6" of hot water from the sun under it just after a couple hours. The new clear one I bought doesn't do that. Its blazing hot out there right now and the cover has been on all morning. I put hand under and the water was as cold as two feet down. Unless it works differently. Filix.
Does clear solar covers realy get the water warmer?
- Thread starter filix
- Start date
Does it actually work that way. No real way to know unless you did a controlled test, using the exact same amount of sun, for the same amount of time, in the same water conditions, etc.
In theory the use of a clear solar cover should allow the light to penetrate the opagaque cover allowing the water to heat up.
The blue on the other hand should not allow the suns rays to penetrate through to the water.
The purpose of the cover is to retain the heat that's already in the water.
I have used both, and currently own a clear. I can say i've noticed my clear cover does warm the pool up when it's on, more than the blue one I used to own.
You should invest in a pool thermometer, take a reading in the morning. Then go out in the afternoon and see if the temp has gone up any.
In theory the use of a clear solar cover should allow the light to penetrate the opagaque cover allowing the water to heat up.
The blue on the other hand should not allow the suns rays to penetrate through to the water.
The purpose of the cover is to retain the heat that's already in the water.
I have used both, and currently own a clear. I can say i've noticed my clear cover does warm the pool up when it's on, more than the blue one I used to own.
You should invest in a pool thermometer, take a reading in the morning. Then go out in the afternoon and see if the temp has gone up any.
The difference is that with a dark cover you're heating the cover which transfers some heat to the top of the water and with a clear cover you're heating the water beneath the cover.
I have a thin blue one for early spring when our blackbirds roll in, when they leave and the real sun starts I put on our clear heavier gauge one.
I believe the clear does a bit better job of retaining heat.
I believe the clear does a bit better job of retaining heat.
Thankyou. I do own a pool thermometer. I have just read that it is still better with no cover at all during sunny days. blizz.
It depends on the amount of evaporation, so in windy areas with dry air the water temp will drop if you don't use a cover. If the cover is truly clear enough, then it will let light into the pool to heat it, but half of the sun's heating is from infrared so the cover should be clear to infrared, not just visible light, if possible. Ideally, it would block UV so that you wouldn't lose as much chlorine.
I have an 8 mil cheapo light blue cover semi-transparent cover. During the daytime, I find that if there is any steady wind, then I need to leave it on. If the ambient temperature is less then 5 degrees above pool temp, I also leave mine on especially if it is cloudy.
Wouldn't that be nice? Passing IR but blocking UV sure would be nice.chem geek said:
So solar covers don't really work. Any cover that didn't sink would protect it from the wind and help hold in heat at night. I think alot of people are under the false assumtion that you buy a solar cover to heat up your pool. When its usualy better if the suns out to leave it off. Filix.
It is kind of an unfortunate name using the word "solar".
With the blue ones people "think" they are "solar"-heating the water more because the top few inches of water are warm from the cover like Bama said. When in reality there would be more benefit to a clear cover allowing the sunlight in for the purposes of heating more of the water.
As chem geek and linen said, if there is any wind, even in the sunlight, you are likely better off with the cover on to reduce the heat loss from evaporation.
With the blue ones people "think" they are "solar"-heating the water more because the top few inches of water are warm from the cover like Bama said. When in reality there would be more benefit to a clear cover allowing the sunlight in for the purposes of heating more of the water.
As chem geek and linen said, if there is any wind, even in the sunlight, you are likely better off with the cover on to reduce the heat loss from evaporation.
We woke up the other morning and there was a blanket of steam coming off the pool. It was so thick it looked like fog. If I'd have had the solar cover on it would have prevented most of that and therefore the pool wouldn't have lost nearly as much heat. Just visual proof of how much evaporation affects the pool.
Are you sure that isn't steam from boiling your water due to the heat you guys see down thereBama Rambler said:
I didn't look for bubbles! 
My water is a chilly 75 degrees right now, even with a cover on it. Hoping it warms up before school starts here in central PA. we had the August heat in June this year. I may have to get a bettersplar cover next year.
My pool has been in the 80s all summer. But it is in full sun 80% of the day. Next week we are going to have some nights in the 50s. Thats when the cover realy helps. Some day I would like to hookup a solar pannel. Those black plastic ones. filix.
We used a blue cover for four years until last year, we went with 12 mil clear. Our observation was the cover worked better heating the water. This morning the pool is at 82 and our nights have dropped into the low 60's the past week.
The biggest thing that helped our pool stay warm was purchasing a solar reel since the kids never put the cover back on after swimming. A good reel that allows you to easily move the cover on/off the pool quickly has made a huge difference for us. Also the wear and tear on the bubbles in non existent since the kids dragged it over the side of the coping before the reel.
The biggest thing that helped our pool stay warm was purchasing a solar reel since the kids never put the cover back on after swimming. A good reel that allows you to easily move the cover on/off the pool quickly has made a huge difference for us. Also the wear and tear on the bubbles in non existent since the kids dragged it over the side of the coping before the reel.
Did anybody actually do a controlled study on this forum? I would like to know if I should leave the cover on or off during the daytime when the pool is in full sun.
All I know is that my pool is bloody cold all the time. I don't think it's ever been 80.
I think a big part of the problem is that it's an inground.
All I know is that my pool is bloody cold all the time. I don't think it's ever been 80.
I think a big part of the problem is that it's an inground.
I have an inground & I leave my cover on during sunny days
The evaporation causes a lot of heat loss, as does the air temp if its below pool temp
I used to have a blue cover & the top 6-8" would be much warmer as long as the pump was not running
With the pump running the water all mixes to approx the same temp...I only have 1 skimmer that pulls water from that top warm layer
Last year I bought a clear cover to allow the sun to heat the water...but without a controlled test kinda hard to say which works better
Does a darker cover soak up more sun & thus transfer water to the pool better ?
Ideal situation might be the blue cover on the water surface, then a clear cover across the pool edge, trapping air in between the 2 which is then heated :idea:
The evaporation causes a lot of heat loss, as does the air temp if its below pool temp
I used to have a blue cover & the top 6-8" would be much warmer as long as the pump was not running
With the pump running the water all mixes to approx the same temp...I only have 1 skimmer that pulls water from that top warm layer
Last year I bought a clear cover to allow the sun to heat the water...but without a controlled test kinda hard to say which works better
Does a darker cover soak up more sun & thus transfer water to the pool better ?
Ideal situation might be the blue cover on the water surface, then a clear cover across the pool edge, trapping air in between the 2 which is then heated :idea:
We just got our pool this year and I have to say that I am very happy with our blue solar cover. Now granted, it has been one of the warmest summers on record for MN, so it may not work as well as next year if this global warming doesn't continue.
However, I think one of the finer points to keeping the water warm is overlooked but was mentioned briefly in a previous post. Having the pump running all the time would help to keep circulating the heat throughout the pool. I am thinking that I am going to begin shutting off the pump at night to see if that helps with retaining more heat and then pull the cover off when it is in full sun with no wind and pump running. Maybe then I will get it back up to that blessed 90+ degrees we had earlier this year
However, I think one of the finer points to keeping the water warm is overlooked but was mentioned briefly in a previous post. Having the pump running all the time would help to keep circulating the heat throughout the pool. I am thinking that I am going to begin shutting off the pump at night to see if that helps with retaining more heat and then pull the cover off when it is in full sun with no wind and pump running. Maybe then I will get it back up to that blessed 90+ degrees we had earlier this year
As described in this thread, about 60% of the energy in sunlight is absorbed mostly by the water in a white plaster pool. A dark pool surface will absorb more. A cover that was clear to light and infrared would let the sunlight through but stop losses from evaporation. A dark cover will absorb the sun's energy, but may not transfer it all to the water depending on the design. If the color of the cover was at the top of the cover, then the bubble insulation below would block some of the heat transfer.
I don't have a bubble cover, but a mostly opaque thinner electric safety cover and when it was light tan there was virtually no extra heating during the day from the sun but with a dark blue cover there is some extra heating, but only 1-2ºF above what the solar system does. If I did not have solar, then I'd see more of a delta between the light and dark colors (having the solar has the water temp be warmer than air temp so there are conductive losses as the cover feels warm).
You definitely want to circulate the water when the sun is out and turn off circulation at night.
I don't have a bubble cover, but a mostly opaque thinner electric safety cover and when it was light tan there was virtually no extra heating during the day from the sun but with a dark blue cover there is some extra heating, but only 1-2ºF above what the solar system does. If I did not have solar, then I'd see more of a delta between the light and dark colors (having the solar has the water temp be warmer than air temp so there are conductive losses as the cover feels warm).
You definitely want to circulate the water when the sun is out and turn off circulation at night.
This discussion is interesting in terms of the visible portion of the light spectrum, but folks, that is only a small part of what's involved in solar heating. Visible light heats up things that absorb its energy, things that look black or at least dark and they in turn heat the air or water around them. Air and water look clear because they absorb almost no visible light energy.
But HEAT radiates in the infrared (IR) portion of the spectrum, which we cannot see naked eye. Water is 'black' in a key portion of the near-IR, which is to say that it is a great absorber of solar heat. (At ~3300 1/cm) Visible light goes down and comes back through > 20 feet of clear water, but IR heat barely gets down 2 feet. So get a solar cover that looks nice and lasts long, and run your pump to circulate heat away from the surface. If you want to convert vis light to heat, paint your pool bottom a nice dark blue or buy a dark liner.
But HEAT radiates in the infrared (IR) portion of the spectrum, which we cannot see naked eye. Water is 'black' in a key portion of the near-IR, which is to say that it is a great absorber of solar heat. (At ~3300 1/cm) Visible light goes down and comes back through > 20 feet of clear water, but IR heat barely gets down 2 feet. So get a solar cover that looks nice and lasts long, and run your pump to circulate heat away from the surface. If you want to convert vis light to heat, paint your pool bottom a nice dark blue or buy a dark liner.