I only have 1 one inch drain. Im running a mag9 return with 3/4 inch return line. My standpip is also 1 inch. Previously, I had a standpipe with a "T" on the top with hole drained in it. That worked ok, but the T hit the glass making the pipe angle, and therefore leak at the bulkhead. So I made a new standpipe, once again with 1 inch pvc, but this time I used an elbow instead of a "T". Now that I have changed the design, the water no longer leaks from bulkhead, but the water goes up and down in the overflow causing the noise. Im lost and out of ideas.