On a sump overflow that is made of pvc, Why do people put a p-trap that is made of 90 degree elbows inside the tank? Why don't they just use a piece of pipe with a hole drilled 1/2 "below the water level, then take it up out of the tank then double 90 down to the sump? This video is an example of the overflow with a trap. I just can't figure out why they would do this. It would be like a sink trap, and over time it would get clogged with debris. Click the youtube link for the example.
http://www.youtube.com/watch?v=0EPvqAYgp ...
Don't need the video, worked with them for years.
The whole principle works on a siphon ... you want to maintain the siphon even when the pump is off returning water.Power fails, you're not home ... who starts the siphon again?
The "trap" maintains the siphon by maintaining water level balance inside the overflow.Drill the 1/2 "hole and you effectively have a" siphon break "... no restart without assistance ... because water level would flow over until level reached hole.Then you are sucking air.
pets question and answers,www.5d2d.com
Doesn't get clogged with debris because water is constantly flowing.Unlike your sink, nobody is brushing teeth, or combing hair, or losing jewelry down the drain .... if you have that much debris in tank, you have a much bigger problem.Water changes do more than freshen things up and gravel vacuuming is done for a reason.
Look at this type overflow in action a little closer.Notice that water turns upward through "trap" and there is a fitting allowing air in at a level just below tank level.The purpose of that is to stop siphon at a predetermined level should power/pump fail.Power comes on tank level rises, balance in "trap" is upset, siphon automatically restarts.
Not a short answer.
Parachromis has is right.
Here is a thread at MFK with diagrams, videos etc that help explain it.
http://www.monsterfishkeepers.com/forums ... Ian
