ald,
The SWCG will use the Pump/Filter relay to make sure the cell is off if the pump is not running. The IntelliFlo itself does not use a relay.
A heater will use a small internal relay. Not one of the 4 high voltage relays..
Any light that you want to control "individually" will need a relay, and if low voltage, a transformer.. If not controlled individually, then only one relay is needed.
If you don't have solar, then you can easily add a 5th relay.
Valve actuators do not use relays.
Thanks,
Jim R.