This is how I control my Spa Electrics pool light with HA.
I have a Spa Electrics pool light that can be controlled via various means including the wireless controller from Spa Electrics but I didn't want to pay lots of $ for a controller that will only get lost. This light can be controlled by turning the power off and on an certain sequences to chaneg the colour. I used a TP-Link P-100 smart switch as the power switch and HA to control that switch.
Details are at Spa Electrics HA controller
Note this light was purchased in Australia so the multi colour buttons maybe different for other countries. eg. "Outback Australia" and "Oceanic Views"