i can by no means take credit for this, but i can tell you from exp. on all my personal tanks and a bunch of others i have built that it is by far the best overflow out there....Not only is it dead silent as he claims, but it is a set and forget system that is fool proof and no way possible for any mishaps or floods......i have never done the internal myself because it takes up valuable real estate in the tank, but done my share of externals.... here is a link to his design with great diagrams and all the info you could ever want or need.....also here is a couple pics of my personal tanks running them external for reference....please feel free with any questions.....btw. i pull 2000+ gallons on a single 1" bulkhead with no sound at all... ask anyone thats seen my tanks in person there amazed how quiet it is....
BeanAnimal's Bar and Grill - Silent and Fail-Safe Overflow System
BeanAnimal's Bar and Grill - Silent and Fail-Safe Overflow System