I have an aqualinks RS4 and I would like to turn on the spa only but the filter turns on and pumps out the hot water into the pool. This prevents the spa from reaching it's full temperature. What is the procedure to stop the filter from turning on when I turn on the spa?

There SHOULD be a valve that you can close to disable the spa.

put your aqualink into service mode. then select components manually this will override any pre-programmed options

This problem can be caused by a couple things. the two most likely culprtits are either the absence of check valves and or incorrect actuator settings when the pump shuts down.

Your spa is most likely higher than the pool. You most likely have a spill over (waterfall) feature from the spa into the pool. This is so the spa water can be recirculated in pool mode. One of your actuator valves may be slightly off closed position in order to allow spill over in the spa, or you may have a dedicated overfill pipe in the circuit to feed water to spa in pool mode.

Whichever spill over piping you have set up, when the pump shuts down, water from the spa ( higher level than the pool) will backfeed through the overflow spa circuit, back through the pump and into the pool through either drain or return. Effectively rendering your spa level the same level as your pool.

To fix this problem, simply install check valves into the spa runs and as a secondary measure put one into the pool return run ( the run that feeds water to pool).

This will insure that when the pump shuts down, no matter which position the valve actuators may be set, water can not back feed through the pump circuit from spa to pool.

If it has motorized valves the stop positions have to be adjusted so that the water coming back is equal to what it drains to stop the spill over process unless you want to add more valves but the pool pump does the job of heating and filtering the spa

Here is a link for the Manual and trouble shooting guide. Aqualink

Trouble shooting guide

AquaLink Trouble shooting guide