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

Automatic pool cleaners, vacuum heads, pool covers,
decks, fencing, pool alarms and security ....
BillD
Pool Enthusiast
Pool Enthusiast
Posts: 10
Joined: Fri 25 May, 2012 08:30
My Pool: 18 x 36 7/11 pool, 92,000liters, Aqua Genie skimmer, hayward 1 HP pump, original 7/11 24" sand filter
Location: Canada

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.


jstars
I'm new here
I'm new here
Posts: 1
Joined: Fri 29 Jun, 2012 09:32
My Pool: In-ground, 20x40 gunite, 30 years old, using blue-and-silver solar cover and Hayward Perflex DE filter -- have done plaster repairs.
Location: United States

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).
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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).
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2381
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

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.
User avatar
mas985
Swimming Pool Pro
Swimming Pool Pro
Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

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.
Mark
Hydraulics 101; Pump and Pool Spreadsheets; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
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.
windsor26
I'm new here
I'm new here
Posts: 1
Joined: Mon 23 Jan, 2017 22:37
My Pool: semi recessed aboveground pool in wooden deck

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

Postby windsor26 » Mon 23 Jan, 2017 22:45

Does anyone know of a pool blanket where the 'bubbles' are locked as a sandwhich between two flat plastic layers. I am fed up with scooping out the broken 'nipples' which come off the blanket when it is removed from the pool., As I now need a new one I would like to get one that will not give me this problem in the future
GlenP
I'm new here
I'm new here
Posts: 3
Joined: Fri 24 Mar, 2017 05:15
My Pool: Above ground 43.5m3, Pentair pump 1.5hp 22m3 per hour, Lacron 36" max flow 31m3 per hour with Zebrite filter medium 250kg.

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

Postby GlenP » Sun 02 Apr, 2017 01:06

Re the broken "nipples" with my last replacement cover I went for one with dog-bone or sort of figure of 8 shaped bubbles, it was called a Geo Bubble cover. It now 3 years old and not one off the bubbles has come apart. The plastic layer that forms the bubble side seems less deformed / stressed around the bubble. Been very pleased with it, about the same weight as previous covers but lasting much better. See link for more info:-
http://www.covers4pools.co.uk/acatalog/ ... overs.html
DSPoolOwner

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

Postby DSPoolOwner » Thu 06 Jul, 2017 23:07

I had used blue blankets for years, but this year I got the grey/silver because it was a heavier mil and I thought it might last a bit longer. My pool is not heating as well. The top 6" now gets VERY hot, but when the water gets mixed up by the swimmers the overall temperature is not holding as well as the blue ones did. Thinking about it.... the blue cover should is blocking out the short wave blue light which heats the blanket and the top a bit, but longer wave reds and yellows pass through and penetrate the water to a depth giving me more efficient and even heating. The grey/silver blanket SEEMS to be catching all or most of the light so that the top layer is heated by the blanket. Since overall temperature is a bit less I'm guessing more light is being reflected/radiated off too. I'll know for sure when September gets here and I see how long my season lasts. I will not get a silver blanket again and will have to consider scrapping this one and getting a blue or clear blanket for next season.

Don

Return to “Pool Equipment & Other Pool Maintenance”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 13 guests