summer cover _ on or off

[nick16]

To heat the swimming pool during the day, is it best to leave the cover on? At present the pool temperature is about 23 degrees, and we are enjoying temperatures of about 30 degrees at present. Somebody told me to leave the cover on in order to raise the temperature, and the next person tells me to take it off and let the sun's rays warm it.

[602]

Depends on the cover but most summer covers if left on will add heat during the day and keep heat in overnight. Just roll back when you want to use it.

[Théière]

Ah the subject of covers, despite a University testing and proving what is best the pool market will still continue as it is for some time yet.

Clear covers allow the full spectrum of solar radiation to heat the pool, coloured covers don't but still do have an effect.

Clear covers do allow the full force of the sun's UV to use up the chlorine if not protected by cyanuric acid and also encourage algae growth. (keep your chlorine level up[I] )

Dark covers block some or all of the sun so slowing the rate of algae growth, black cover do absorb more heat but being black also radiate more heat especially at night.

Having no cover does mean the spectrum of the suns rays will potentially warm the water but any gains will be short lived as both wind chill and evaporation off the top of the water would quickly negate any gains.

Best analogy is a green house, no roof = no heat!

Black roof = very hot roof, that's all!

Glass roof = you get very hot inside!

[nick16]

Thank you both for taking the time to reply. I will be leaving the cover on, except when swimming, which with the current weather, looks like lasting into October - another first.