I think there is a miss communication. Where is your noise? I thought it was coming from the end in the sump where the water from the tank goes... If it is straight down all the way from the top of the tank then you really can't shorten the fall unless you add in some bends. Mine happens to have bends in it so I can change some things around. I wouldn't recommend dropping your overflow lower.
Nope, my brain was just moving too fast and I was talking about another part rather than the previous noise.
The previous noise was the gurgling, which I seemed to have taken care of with the airline tubing. This was in the outside overflow box that hangs on the back.
The recent noise is the sound of water cascading through the grooves on the inside overflow box. It has settled down a little but it is still a little loud. The water on the inside is not even with the water on the outside.
Your build is great,but IMO,you know what they say about opinions,you might won't to revise one thing.
The plastic containers you are using will contract and expand with the weather and pressures inside the containers.I think you will find that you will continue to have problems with leaks and possibly cracks in the containers eventually.
I would suggest replacing them with a an 20 gallon aquarium.You could still cut the sides out of the containers where you have the pipes and insert them in the aquarium to give you your compartments.
I'm sorry and honestly I think that is a concern you should have.
Valid point. I'll wait until that happens before I replace it, because honestly, I am burnt out!