I refilled the pool today. In 8 hours it has heated up from 21 to 35 degrees. The pump draws 2 KW. At a price of 0.2 CHF per KWh, that's 3.20 CHF. I would calculate the pump (without heating) with approx. 200W, it should run 8h per day -> 30 centimes per day. The CHF 40/month seems realistic to me.
Depends on whether you always heat up fully for 24 hours... I pay approx. 40 per month for electricity and have set it to 38 degrees, but only at weekends, otherwise 28 degrees.