I am in the process of winterising my inflatable hot tub.
The first thing I noticed was that the inflatable "body" is heavily discoloured by mould that is growing inside it:
I assume that the cause of this mould is the excessive amount of water that was present inside the inflatable ring itself. By various means, I have removed around 3-5 litres of water from within the inflatable cavity.
I have no idea how this water got in there - my calculations give a maximum amount of water vapour in this volume as around 25 millilitres. But that's another story.
I'm looking for ways to 1) dry out the remaining air inside, 2) kill the mould. Bear in mind that I have a single inflation hole - around 25mm (1 inch) in diameter - through which I can operate.
I've tried warming the surface with a heat gun to get the water droplets to evaporate - but this is ineffective and risks melting the plastic.
I've tried deflating and reinflating a few times, in the assumption that it will replace with drier air each time, but the condensed droplets remain.