Water Dropping with Return Pump

[Drewb628]

I have a new IM 170, and I have the return pump turning off during feeding. My issue is that the water level in the tank drops 3-4 inches whenever the return pump is off. It is well below the outlet where the water circulates back to the sump. It also, as you can imagine, fills the sump up significantly. I imagine that water is still draining down when none is coming back up from the pump being off, but that seems like a big swing. Is it normal to have that big of fluctuation with water level when the return pump is turned off?

 

[Fish Fan]

Are the returns in the tank pointed down so much that a lot of water is back siphoning through the return jets and into the sump? In other words, does the tank drain down to the level of the return jets, and can you try to raise them to prevent this from happening?

 

[Drewb628]

Are the returns in the tank pointed down so much that a lot of water is back siphoning through the return jets and into the sump? In other words, does the tank drain down to the level of the return jets, and can you try to raise them to prevent this from happening?

I'm such a dummy. That's exactly what was happening. Reoriented the returns so they weren't sucking all the water down into the sump. Thank you so much!

 

[exnisstech]

Drilling a syphon break in the return line can help also.