I have an overflow on my 55G and everything is fine. The only time the syphon would break (never has for me) is if you have a air in it to start, also weak return pump that cant keep pressure on the syphon. I agree best to go with a drilled tank, but overflow can work well...

Quote Originally Posted by allan View Post
Be sure you do go with a drilled tank. Don't be lured
by a cheaper alternative like an overflow sump. They are more prone to losing its siphon which will result to an immediate water change and a lot of mopping.