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

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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.


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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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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