Ok guys. This weekend I set up the 180 which has dual overflows. Im having a few flow, sound and restrictions issues.

The break down Durso stant pipes have 1 1/4" sch 40 pipe, which drain into 1" sch 40 pipe underneath. Im thinking that right there is my problem going from 1 1/4" to 1". The drain on the right also has to travel further and has 2 90 elbows to go through. The hole drilled on top of the durso to allow burping is just a little smaller than a 1/4".

I have my mag 18 return turned way down with the use of two ball valves on each return line. Ive had it on with the ball valves fully open the overflows seem to be able to handle it but it soulds like loud toilet flushing and theres a lot of bubbling and fizzing in the sump.

Some pics for reference

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