I need help with fiji cube aio insert

[Bluejillo]

I have a fiji cube gen 1 aio insert in my 40 gal tank.... Its a little too tall so i had to dremel the teeth down quite a ways. The pump chamber empties faster than it refills. I cannot add anymore water to the tank or it will overflow and ive turned the pump all the way down.... Im at a loss... Do i keep extending the teeth or is there something im missing?

 

[Reefersutherland_]

I think I see what the problem is. I think you need to drill a hole in the dividing wall in the filtration area. Or smaller pump

 

[Bluejillo]

I think I see what the problem is. I think you need to drill a hole in the dividing wall in the filtration area. Or smaller pump

A smaller pump seems to be the consensus. Im thinking a reef breeders DCA2000 so i can control the flow better.