I have an error code on my Aqua Logic contol that says - Check system spa sensor open. The manual tells me what this means but not how to remedy.

I assume you have a separate spa, meaning your spa is not connected to your pool, and has separate equipment for it.
If this is the case then your water sensor for your spa is bad, or the wire to it has been broken.
The water sensor is a little black thing that has been drilled into the return pipe at the pool equipment, and has a metal clamp holding it in place.

If your pool and spa are connected, and share equipment, then you need to change the setup of the Aqualogic to "shared equipment" which will get rid of check system light.

Thanks for the reply, appreciate it. My spa and pool are connected and I have the Aqua Logic set to "Dual". I guess that's the same as what you refer to as "shared equipment". I replaced the sensor today and still get the error message "Check System Spa Sensor Open". Could it be the PC board?

When I set the pool/spa setting to "STD" and not "Dual" the check system light goes off but will the pool and spa filter together at the same time at this setting?

Has anyone used an Arctic Glacier Pool Cooler? Is it worth it to install one? My pool water is 94 degrees, too warm to for swimming. Be nice to get a full season of use especially here in Texas.

I had a similar problem with my pro logic controller which gave me the "spa sensor open" error when i choose the "dual" setting in the configuration menu. After studying the manual it seems that the "dual" setting if used for unconnected spa and pool. I have a spa that spills into the pool so i used the "pool and spa - std" configuration and the error went away and everything is working fine. I think what happens is that in the "dual" setting the spa looks for a spa water sensor and can't find one because shared pool/spa systems only use one sensor for temperature.

I am very new to pool ownership so experts pls correct if I am wrong. Just had this problem, read about it and seemed to fix it.