Many thanks for your prompt response.
Unfortunately, there isn't an option on our tub to have jets on low - it's full blast or nothing. When we turn the jets on, the meter goes into overdrive and spins about 6 times faster than it would do normally, so I do know it's the jets driving this.
There is a small outlet that blows bubbles into the tub every so often, which I assumed was what measured the heat and kept things ticking over.
Sorry, I thought Balboa was the brand? There's no branding on the actual machine - it's a TP600.
It was the company we bought the tub from who told us we only needed to set the filter to come on once a day.
We weren't given any diagrams of the circuit board or electrics tec., I'm afraid.