Are your hot tubs insulated?
Usually, no insulation is needed as Gardenvity hot tubs with insulated covers maintain the heat very well. For example, suppose you heat the hot tub to 39°C in the evening and keep it overnight covered with an insulated faux leather cover when the outside temperature is around 15°C. In that case, the water will cool down by about 2 degrees, which means that almost no extra heating or just a short one is necessary.
We can insulate the fibreglass liner for an extra fee of £150 for use in colder climates, if necessary.