Hot tub contained by uk is it cheaper to turn the temp down at hours of darkness and afterwards bake it up previously you use it? it has a 1.5 kw radiator and I recon it takes...

it has a 1.5 kw radiator and I recon it takes simply over an hour to raise it by 1 amount.
I like it (a) 35 degree c . Is it cheaper just to hold on to it at 35 all the time or agree to the temp drop and then steam it up
Thanks for any answers I am trying to save the planet :-)
Answers:    no, costs you more and uses more animation trying to reheat the water, bestow it on one temp.
put it on a timer you can set it to what ever you want day or darkness once done you do not have to tutch it again till you want to correct the setting