Control the temperature of my home spa with Tibber/Homey

Hello!

I am a complete newbie when it comes to smart homes so bare with me. We bought a new house and we will move in about a month.

We have a Nordpool Abisko home spa and I want to heat it up when the spot-price is low.
I bought a Homey Pro that I will connect to Tibber (with Pulse) connected to my Nibe for smart heating.

What are the gadgets I need to make this work? I guess some kind of temperature sensor and some way to turn on/off the pool heater. How would a flow for this set up look like? I am thinking I need to set an interval of temperature and have Tibber to optimize this.
For pool owners out there, is there a โ€œminimalโ€ temperature that I can set to save energy when we are not using the spa? I will see how long it takes to heat it up and in the case of it taking a few hours maybe I can have a button/app command to set the heater to max temperature and get a notification when the ideal temperature is reached.

Any input is appreciated! thank you

Waterproof thermostat and a smart plugg or Plejd could work. Just make sure that the spa activates as you want when you power it off and on (i.e. it starts to heat). If it does, the flow is quite simple. Something like:

WHEN temperature > 40 AND Tibber price is low
THEN start Spa