I have always thought along the same line however, like Ctoon, I now have a darker vinyl lined pool whereas my last pool was a light colored fiberglass (moved) and the temperature is about the same with the same amount of exposure to the sun. Kind of blew away my deduction but it always seemed logical? :?: :?:HappyWino said:....a darker color will absorb more heat and reflect less, the opposite being true of a lighter color. I would therefore speculate that a darker color will absorb more heat that will then be released into the water through convection/conduction whereas a lighter color will reflect more heat away.
This is true but it has more to do with the energy conversion and heat transfer. The pool surface temp will not be that much different since heat transfer is pretty quick from the pool surface to the water. So the pool surface will absorb energy and thermally conduct it directly to the water. So even though the temp difference is small, the surface will still transfer BTUs to the water.DavidD said:Maybe, but if you feel the walls/floor below the water line isn't it the same temperature as the water even if in direct sun light?
This is also true but there still may be a net heat gain since the water takes the heat out of the surface almost instantaneously so the dark surface will be at the same temp as the water (see above). Any remaining energy in the pool surface that radiates back, some of it will be absorbed by the water again.chatcher said:Since dark-colored objects both absorb and radiate heat more readily than light-colored objects, I would think whatever additional heat might be gained while the sun is shining (if any!) would be offset by similar losses when it is not.
Good Point.mas985 said:.....since heat transfer is pretty quick from the pool surface to the water. So the pool surface will absorb energy and thermally conduct it directly to the water. So even though the temp difference is small, the surface will still transfer BTUs to the water.
Yes, as have I. When buying our new house, I even commented to the wife that with the dark liner, this pool should actually stay warmer. It doesn't feel that way yet but it has been getting down into the 60's on some night. I guess the wife is really missing the heat pump.....mas985 said:.....I have read from many sources that you can get close to 1-2 degrees of net heat gain with a colored surface so I do think it has a small effect on temperature..
A lot of people use their solar panels to cool the water at night, which I would think work mostly by radiation.mas985 said:...At night most of the heat loss will not be radiative but evaporation from the surface...
...There are so many processes going on with heat transfer that it is really difficult to know for sure if there is heat gain...
Sorry if I seem skeptical but I think something else besides pool color is contributing to the temp difference. I don't think the physics can support that. Without solar, I doubt very much any pool could be 14 degrees wamer than another without other important factors involved. Pool water itself is fairly efficient at capturing heat. However, retaining the heat is dependent on other things such as a pool cover. Nightime exposure would ensure that most of the heat gained was lost each day. This hapens for me with solar panels when I do not use a cover. For a fair comparison, the following must be true.mathey said:talked to my neighbor yesterday... his temp is 72, mine is 86
he said his liner is almost white now (12 years old)
both pools are located about 300 yards apart, both get full sunlight all day...his faces more north/south, mine more east/westmas985 said:Identical time exposure to the sun (# of hours and time of day) between pools.
i'd say i probably get more wind, he has a solid fence, closer to the edge of the pool, mine is open and at its closest, is 8 feet from the pool...his is also tucked up closer to the house than mine.mas985 said:Identical wind exposure between pools. If he gets more wind than you, his pool will be cooler.
we just put the cover on last week, and even before then we were at 82-83 (yesterday we were up to 88 with the cover)mas985 said:Identical use of pool covers between pools. This is a big one. If you use a cover and he does not, that will make a big difference.
both are 16x32 grecian style, his corners are not as long as mine, so he may have a tad bit more volume and surface area (I mean a TAD)mas985 said:Identical surface area to volume ratios. The amount of sunlight captured is proportional to the area of the pool but the BTUs required to raise to a certain temp is dependent on the volume of the pool. If you have more surface area to volume than another pool, your pool will heat faster even with the same color.
I can't speak to this, I know my water is warm, and he almost never gets in his since its too cold.mas985 said:Thermometers are working properly in both pools. I have seen too often bad thermometers.
It's not all in your head...while my pool was filling with cold water from the hose (municipal water supply), the dark liner walls were considerably warm in the midday sun and the water in the pool was around 78 degrees. This was at the 11,000 gallon mark in a 23,000 gallon in-ground vinyl pool. Perhaps any color liner would have been warm with direct sunlight striking it but I strongly suspect that the dark liner absorbs more heat radiation and releases it back into the water.Maybe it's all in my head, but I'm very glad I got the darker color liner!