Melev's Sump page:
http://www.melevsreef.com/allmysumps.html
Overflow/Drain size calculator:
http://reefcentral.com/index.php/dra...flow-size-calc
Head Loss Calculator:
http://reefcentral.com/index.php/head-loss-calculator
The Herbie style of overflow is the only way to go in my opinion. Quiet, Safe, and little to no microbubbles instantly. If you plan on running your tank indefinitely it is well worth it to find somewhere or something to put you current livestock into so that you can bring your tank into a glass shop and have it drilled for one.