Hi, I have had this tank up and running for a long time and can't recall this situation. I have to sumps, separate intakes and returns. They are however plumed together. This is the first time I ever recall they are sitting at different water height. What could be causing this? The two pics show in red line the height of each. Not sure how the one side of the left sump is so raised, is this concerning? Any help would be greatly appreciated. Thanks
Your pre-filters are probably due for a good cleaning/rinse. If flow is being restricted at that point, it will definitely affect the water levels shown in your sump(s).
NOTE: As they are plumbed together, the level will correct itself when the pumps are shut off. You will notice this when the pumps are running and the water flow is actively running.