I've had my Apex for almost a year and a half now with very minimal issues. In the last few weeks, my Salinity probe is giving me readings that jump every day. I have re-calibrated the probe three times with the temp offset and without to no avail. I have taken the probe out, rinsed it, dried it, made sure there were no critters or buildup inside (that I could see anyway). I've unplugged the other probes and even isolated the salinity probe wiring. But for almost the entire last year and a half, I have had no issues with this.

It seems that every night at 11pm the salinity jumps from around 29 to around 38 and then at 4am the readings go back to around 29. When I test the water, my refractometer is always around 35 (or 1.026) whether it's day or night.

I have no other items that are near this schedule (lights turn off before 11pm and turn on well after 4am). My ATO activates roughly every 45 mins or so (and the pump is in another room). I'm attaching the ApexFusion graph below.

Any help is appreciated!

salinity.jpg