plumbing problem!

[jeremyj0247]

so I am setting up a 38gal display with a 20L sump. I set it up with one inch drain and 3/4 return with a mag3. This gives me around 300 gph which is good for my setup. My problem is that I did a test run today and everything is so loud. It seems like the drain is flowing way to much for my pump to keep up. I put a ball valve on the drain to slow the flow down, but I can find a happy medium. Either the flow is too much and everything is noisy or there is not enough flow and the display will overflow. Should I switch the drain to 3/4. If I were to do this, I have drilled a hole for a one inch bulkhead obviously so can I just neck the pipe down to 3/4 out of the one inch bulkhead. Does anyone have any advice for me. Thanks for any help.