I’m having issues with my reef tanks water levels. The water level in the return pump section is constantly changing and it is not due to evaporation. I know this because for the past two weeks I have had my ato off. I have been manually topping off the water and then a couple minutes later the water level will drop back down. I would refill and then the water level would be constant and then a couple hours later the water level will be higher than where it was topped off to. The water level in the display tank is also shifting and never stays the same. I just upgraded the pump so I know it’s not due to the return pump. There is one main drain with a gate valve on it as well as one emergency drain. I’m not sure what is causing the issue. Any help would be appreciated.