What Color Solar Cover Works Best?
When trying to choose between different color solar covers, you should understand first the effect that the blanket has on the pool in the first place.
First, a blanket prevents heat loss through evaporation. Evaporation is the leading cause of pool water heat loss (like when the pool water cools quickly at night). All covers are generally equally effective at preventing evaporation heat loss. Secondly, a blanket prevents heat loss through insulation (this effect only works at night, when the pool water is warmer than the surrounding air). For this, again color doesn’t matter, though covers with embedded air bubbles are more effective.
Next, a solar cover, or blanket, can add to heat production via sunlight. Direct sunlight is the biggest contributor to raising your pool thermometers temperature. This is where color matters. A black cover absorbs more sunlight at the cover itself, making it much hotter. On the other hand, a clear cover lets more sunlight through to the pool itself, letting the water absorb the sun’s radiation.
This begs the question: which is more effective? The answer depends on whether you’re looking for the quickest heating, or the highest temperature. The black cover will heat a cold pool faster as its surface quickly absorbs the sun’s rays… but it will reach a lower overall temperature. This is because the high temperature gradient at the cover itself means increased heat loss due to surface radiation. The clear cover transfers the solar energy somewhat slower…but ultimately will reach a higher temperature. Covers with a blue or silver color will produce effects somewhere in between those of the black and clear covers.
In the end, the final results between the covers will only vary slightly – by a few degrees in water temperature. Clear covers do tend to last longer though as a darker cover will breakdown faster as its greater light absorption leads to faster deterioration.