Where did everyone put the apex probes? I have mine in the center sump downstream of the ato input (in the far right where water enters), and I can see a drop in temp when the ato is on. I also have it downstream of the dosing input, but I haven't started dosing yet to notice.
My probes are in the right side where all the water drains into the sump. Heaters are in the same section. I have my dosing tubes on the left side right above the return pump.