Need help plumming a 40 gallon breeder sump to a 120 gallon tank

[mariegibson202]

I recently picked up a 125 however the previous plumping had to be cut in order to move the tank. There are 8 overall holes drilled into the back of the tank. Looking for any suggestions, general tips, or designs since I plan on redoing it all! My plan is to have three holes in the middle, shaped like a small v, as intakes. The highest holes on the side as returns and seal the remaining holes. A 40 gallon breeder will be used as a sump below the tank.

 

[lapin]

I took a used tank with a lot of extra holes and used 2 for a closed loop.

 

[Snoopy 67]

Using them as returns opens up a BIG can of worms.
What happens when the power goes out & drains the tank down?
Check valves WILL fail @ THE WORST TIME!
Closed loop sounds best if you still use them.
OR cap them off.