IIRC, Hydro Spa went out of business in 2007, so the unit is somewhere 7 years old or older.
I replaced my spa pac, and memory is not as good as it used to be, but I'm pretty sure the original pac on my 2000 model Hydro Spa was a balboa.
Mine uses a 2 speed and heats on low for one side, other side is single speed.
I'm thinking my adjustment for the pressure valve is on the board. Ake, did you just replace the sensor, or did you also adjust the setting?