Solar pool heating via a dark screen -- On the surface or submerged?

[mmk8283]

TL;DR Summary

Looking for input on either floating or sinking a large sheet of dark screen for solar absorption in a pool

Summary: Looking for input on either floating or sinking a large sheet of dark screen for solar absorption in a pool

Looking for input on either floating or sinking a large sheet of dark screen for solar heat absorption in a pool. My though its that screen would be very user friendly to roll up when using the pool, and also cost effective. My question is if there is a trade off between the gain in solar heat absorption vs. creating artificial shade in the water column if the screen was to be on the surface. Any thoughts are appreciated!

 

[berkeman]

Welcome to the PF.

Part of effectively heating a pool with solar energy (via pool covers) is to limit the amount of heat given up to the air. Can you see how a porous screen will not do a very good job of that whether floating or submerged?

 

[mmk8283]

I understand that the screen will not prevent the natural rise and dissipation of heat to the surface. But won't it still gather more solar heat vs. having nothing at all? Thanks for your help and input!

 

[berkeman]

Yeah, it's probably better than nothing. Kind of like having the bottom of the pool painted black, but who wants a pool with a black bottom?

But better still would be to just buy or make traditional covers, I think. Or use a non-porous fabric that sits on or just below the surface.

Have you tried any Google searching on this? I'm not 100% sure what the best solution is...

 

[DaveC426913]

I use a bubble wrap cover. Here's why it works:

Something like 90% of the heat loss in a pool is from evaporation. A floating blanket stops this. Very effective.

The transparent cover let's sunlight right through to heat the pool water directly. (While a black cloth will absorb sunlight, it will only transfer via conduction to the topmost layer.)

It floats.
It's super light.

 

[Rive]

The transparent cover let's sunlight right through to heat the pool water directly.

And since water is transparent almost only in the visible spectrum, the good type of cover will produce a very good greenhouse effect too.
Or, at least something similar

 

[Baluncore]

Something like 90% of the heat loss in a pool is from evaporation. A floating blanket stops this. Very effective.

That is correct and very important.
Float the cover so as to reduce evaporative cooling.