"Jerry Baker" wrote in message news:%fTRg.2551$422.228@trnddc03...
Wayne Sallee wrote:
What makes you think that you have reached the limit?

Because any increase in flows causes the drain to gurgle constantly as
the air tries to bubble up through the falling water. Inserting air line
into the drain doesn't help. The water occupies all of the sir space in
the pipe until the air burps out.

Look up the "durso" keyword. Allglass tanks come with nice durso pipe.
This pipe does not gurgle as much as the typical one...
You can buy guts to the Allglass overflow as a separate kit.
It might match your tank holes.