This is a second hand tank setup so I’m trying to make some improvements. I raised the weir on the tank to raise the water level in the display to the trim. Now the water is falling 2 inches or so over the weir to the level of water in the overflow which is quite loud. The issue I have is I can not raise the drain pipe much (half an inch) because of a glass lid and the air vent. The only thing I can think of is to reduce durso air vent which current sticks up around 2 inches. Any other thoughts or issues?