Solar blankets / covers: blue vs. silver back vs. clear

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jlfitzpatrick

Solar blankets / covers: retractable?

Postby jlfitzpatrick » Mon 30 Jan, 2012 19:25

[quote="Joseph2010"]I
I don't use my 16 x 43 foot inground pool as much as I would if the solar cover could be easily retracted by one person. I hear nothing good about the "hand wind" devices. I LOVE my blue solar cover and need it in CT. Anybody have an electrically or mechanically retractable cover that works - or know of such? Thanks in advance.


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Solar blankets / covers: blue vs. silver back vs. clear

Postby chem geek » Tue 31 Jan, 2012 11:02

I have an electric mostly opaque safety cover from Pool Covers, Inc. as shown closed and open. We now have a dark blue one instead of the tan one shown in the photos. The cover seems to need to get replaced every 3-4 years while some of the hardware gets replaced after 7 or so years. So it's not cheap and one should figure that on average in the San Francisco Bay Area it's around $350 per year (in peaks of $700-$1200) so more expensive than replacing a bubble-type cover every couple of years. That's the price for convenience.

My chlorine usage is a lot lower even though the pool is used everyday (in the summer) with < 1 ppm FC per day chlorine demand. Most residential pools without a cover exposed to sunlight have 2-3 ppm FC per day chlorine usage.

Unfortunately, I don't know who does electric solar cover installations in CT.
John75

Solar blankets / covers: blue vs. silver back vs. clear

Postby John75 » Sat 10 Mar, 2012 19:29

Hi Bailey! Have you checked this guide to swimming pool covers at www.indoorpoolguide.com/pool-covers
Duke of Joke

Solar blankets / covers: blue vs. silver back vs. clear

Postby Duke of Joke » Wed 02 May, 2012 00:07

[I use my pool vac under the cover to really move the water around on real hot days!][/quote]
Joseph2010 wrote:I see Folks are confused as to How to get the most from their Solar cover.
Know that having your cover sit in the Sun AND that chlorine will break down your cover. Don't over chlorinate and either cover it or get it out of the Sun. Yes - it would be a pain to move it all the time BUT you have to decide IF you want to have it LAST longer. Fortunately the end of MY pool, where the reel resides, is shaded by trees :).
Here is what I have found to work well to heat the water best. Know that heat rises. We have all detected the first few inches of water under the cover is hot. Whilst the Solar pool is on the water, select to have your filter on 'full bottom drain' - the bottom of the pool is where the water is the coldest. The filter will draw the cold water nearest the bottom through the bottom drain sending it back into the pool. As the inlet is closer to the surface of the pool the cold water will then MOVE the hot water - mixing it with the cold water. This then places cooler water just under your cover for solar cover heating. This also helps protect your solar cover from getting too hot. A cover getting too hot will split the layers.
Additionally be mindful to the fact your inlet assembly can be 'adjusted' to direct the water directionally as well as up and/or down. I have my inlet adjusted to direct the water just below the cover but not too close to the surface so that the cover will not 'travel' from the force of the water but yet enough to move that layer of hot water around. This will always supply cool water from the bottom of the pool under your cover.
Of course the bottom drain will help 'pull' the water down also.
P.S. - some of you may 'think' that full skim will draw the hot water through the pool best BUT - because of the location of the inlet being (high on the sidewall of the pool) you will have , by doing this, allowed that cold water to remain at the bottom of the pool. I have tried both ways by the way - my suggestion DOES work BEST!!!
Ummm - there will NOT be a charge for this guidance - a round of applause will do.
getting back to the question

Solar blankets / covers: blue vs. silver back vs. clear

Postby getting back to the question » Sun 20 May, 2012 17:41

Getting back to the original question. I'm trying to figure out a consensus. Looks like clear covers win.
BillD
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Solar blankets / covers: blue vs. silver back vs. clear

Postby BillD » Thu 31 May, 2012 14:16

I have only used the clear blue ones, and they work best when on the pool. You really need to look at how they work. The air in the bubble gets heated and water flowing across the cover absorbs the heat. If the heat isn't absorbed the bubbles get so hot they burst. so, it is important to draw heat across the blanket to get maximum heat transfer and extend the life of the blanket. As well, when on the roller, the blanket needs to be covered to protect it from the sun. If you want a dramatic comparison of the difference between a clear/blue cover and a black opaque one, put both on some grass and see what happens. The other thing the covers do is prevent/reduce evaporation,and evaporation cools the water.
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Solar blankets / covers: blue vs. silver back vs. clear

Postby jstars » Fri 29 Jun, 2012 09:53

I have used clear solar covers up until this year. They heated up the pool really well, but did cause algae to form (but that could have also been because it did such a good job warming the water!).

I started using a Blue-Silvered cover this year and after more than a month of constant covered use (with pump running during the sunniest 6 hours of the day the pool has only gone from 68->78 degrees so far, hitting 80 only once. I like to keep it into the 80s (and in NewEngland you have to Bank as much heat as possible to stretch the short pool season up here).

The idea about pulling more cold water thru the bottom drain and sending it to the top to mix with the warm sounds pretty good. I think my pump system is doing maybe 2/3rds bottom and 1/3 top now anyways. But I might even put a cleaner hose permanently into the skimmer and let it dangle down into the pool bottom so it no longer 'skims' (and maybe does some cleaning down there too).

Thanks for the good ideas on this.

J
Dmanf

Solar blankets / covers: blue vs. silver back vs. clear

Postby Dmanf » Mon 29 Apr, 2013 17:53

Did an experiment:
I used two identical cold tubs of water and covered on with a translucent blue cover, and I added a black layer to the other. There initial water temperature was 55. By the end of the day, they were 82 degrees. (8x18x4 inches water). POINT: The black plastic over the bubble cover did not affect any change whatsoever. The black may absorb more sunshine, but the opacity prevents solar penetration. All these covers with different color bubbles are marketing, marketing, marketing. I went with blue at half the price (and admittedly half the warranty. The warranty is essentially worthless anyway).
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Solar blankets / covers: blue vs. silver back vs. clear

Postby chem geek » Tue 14 May, 2013 15:25

If you were to have compared with a white opaque cover, then there would have been far less rise in water temperature. Basically, the translucent one lets light through that heats the water while the dark opaque cover absorbs the light so gets hot and can heat the water that way though depends on where the black is -- if at the top above the bubbles then heat won't get transmitted very much (and instead it heats the air more than the water) but if on the underside touching the water, then heat should pass to the water.

We have used a light tan opaque electric safety cover on our pool in the past and then switched to a darker blue opaque cover and noticed an increase in water temperature with the latter of a few degrees (but we mostly heat using solar so the temperature difference would be greater if we didn't have any other heating). These are not bubble-type covers so are just comparing the difference in color. The covers are only about half as insulating as a good bubble-type cover which is why the darker one was able to pass heat through to the water.
Chris in upstateNY

Solar blankets / covers: blue vs. silver back vs. clear

Postby Chris in upstateNY » Fri 31 May, 2013 07:09

One of the original questions asked related to heat retention. All the replies seem to only discuss heating capability and impact on chlorine levels.

I have an 18x32 IG in a yard flanked by tall trees on the south and west. Definitely not 8 ours of direct sunlight even at the height of summer. I live on a hill in upstate NY. Gets very hot in the summer, but can get cool at night. I have always found that for me, the cover is more blanket, and less solar heater, in that the key is having it on at night to prevent heat loss. A secondary benefit is having it on during the day on sunny days when the pool is not being used. But for me, that heating function, though important, has been secondary to the blanket function.

My cover just went to the dump. Light blue, round bubbles - no idea what mil. It tore and was taking on water, and became too difficult to take on an off, especially for my wife, thus limiting use.

SO. - I need a new cover and found myself as confused as the original poster. The cover needs to:

1. Retain heat at night (I really don't care why I.e. whether due to evaporation prevention or whatever).
2. Provide solar heating during the day on hotter sunnier days. Note that per Joseph's comment, I do have a floor drain and do not have a dedicated vacuum line).
3. This is a biggie: Be Manageable to take on and off - not too heavy, not difficult to crank on the roller, not too heavy for the roller.
4. Last for at least two seasons for every $100 of cost.

Recommendations as to color, thickness, manufacturer, and design would be appreciated, addressing w
Each of the four criteria. Thanks in advance for any responses.

Chris in Syracuse
JPME

Solar blankets / covers: blue vs. silver back vs. clear

Postby JPME » Wed 26 Jun, 2013 08:38

I owned an above the ground pool for probably a little over 16 yrs. In that time I've had every type of solar cover. My honest opinion is that black heats best. If you look at solar cell, solar heaters, solar anything they're always black; to absorb heat. And like someone said in a previous post, just make sure your water circulates from top to bottom.
DonS

Solar blankets / covers: blue vs. silver back vs. clear

Postby DonS » Thu 15 Aug, 2013 22:22

I've been covering my pool for 30 years in the San Jose Bay area. Most of the heat loss from a pool is from evaporative cooling so ANY color pool blanket will eliminate that and will keep debris out as a bonus. We have little grandchildren right now and we're getting to be old wimps so I let the pool get as hot as it wanted and I've left the (light blue) blanket on all the time when we weren't swimming. This has been the coolest summer I've ever seen hear which was great for golf, but seemingly bad for swimming. Despite that I've been able to have a pool near 90 even when the daily high is only mid 80s (low high 50s) for weeks in a row. Helping it along I have a variable speed pump (Pentair Veriflow) that runs all day long at slow speed and keeps the water circulating.... that helps transfer the warmed surface water around the pool better and has really helped avoid algae problems and warm my pool better. I also try to wash the cover off once a month to keep it from getting too dirty. I only get 2-3 years from my covers and I've resigned myself to that cost so I tend to laugh at a 5 year warranty (which quickly dilutes after 2 years normally). My experience is the blanket gets you +10F, meaning it would be 80 degrees here in the summer without a blanket (low humidity means more evaporative cooling and cool nights).
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Solar blankets / covers: blue vs. silver back vs. clear

Postby chem geek » Sat 17 Aug, 2013 00:00

Without a cover in the S.F. Bay Area the water temperature if exposed to sunlight will get to roughly a little more than the average day/night temperature so for San Jose, CA in July and August with an average high of 82ºF and an average low of 58ºF, the pool would get to just a few degrees above 70ºF. The heat gain from the sun during the day, which is also limited by evaporation during the day, is offset by the heat loss from evaporation at night. So your cover is doing more than just 10ºF and is probably more like 15ºF (you may be in a somewhat warmer area of San Jose, so water temp without a cover might be 74ºF).

That sounds like your cover isn't that dark or opaque and you mentioned it was light blue. So I suspect that it is letting light into the pool so that would account for the greater heat gain since there won't be loss from evaporation and only from conduction through the cover (pretty minimal for a bubble-type cover) and walls and floor of the pool. The better insulating bubble-type translucent solar covers do get around 15ºF heat gain.
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Solar blankets / covers: blue vs. silver back vs. clear

Postby mas985 » Sun 18 Aug, 2013 17:38

I have a clear cover and when I have my cover on, I don't need solar. I can easily get 15 deg above what I would without the cover so 84-86 degrees is easily achievable through most of the summer.
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jncressman

Re: Solar blankets / covers: blue vs. silver back vs. clear

Postby jncressman » Sun 19 Jun, 2016 10:34

White or silver will be the best if you want a warm pool.

During the day take the cover off. During the night put it on.

This is what you should have learned in high school physics. Heat is transferred by 3 methods - convection, conduction and radiation plus the pool will also loss heat through evaporation. We don't need to worry about losing heat through convection, we lose very little by conduction and any cover will stop evaporation. So radiation is our main reason or pool temperature drops at night. A clear night sky has a temperature of -270 C. Now your high school physics teach should have shown you that a black object will BOTH absorb radiant heat from a warmer object better than a white object and it will radiate heat more than a white object. (most processes in physics work the same way forwards and backwards). So if you want to absorb heat you put a black blanket on but there is no heat to absorb at night. At night you want something that doesn't radiate heat, so you want the whitest (highest albedo) blanket you can find. The gold Mylar film used on the International Space Station would actually be the best.

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