Draining issue

[Chris1998m]

Hi guys, my aquarium isn’t draining very efficiently, only a small trickle into the sump and my return pump keeps starving. If I add more water the water level in the aquarium rises to the point where it nearly overflows. I can get the balance just right, any ideas or tips thank you in advance

 

[19Mateo83]

Pictures are worth a thousand words

 

[Chris1998m]

Pictures are worth a thousand words

 

[Chris1998m]

So in picture 1 you can almost see the water draining into the pipe in it aquarium, picture 2 is obviously the return pump, it’s not usually that high I’ve just put some more water in it, there’s usually about a 1/4 less in there, and the video is the flow into the sump

 

[parclife]

Is that your emergency overflow pipe and is there a main pipe submerged?

Also what type of valve do you have and have you tried opening it more to let more water flow through?