Thanks for your help! I was thinking the same thing like dang I wish I would've just did a flexible tube from the bulkhead down to the sump to begin with it would probable been a lot quieter. But just to confirm, yea it has an internal overflow.A single 1.5 inch drain should be adequate for this size tank. Not the way we would do it but adequate for the volume you need to drain. I looked up your aquarium and am not familiar with this brand. The image I saw shows internal overflow. If that's the case then using flexible tubing and adding soma curves should take care of your noise problem
