why do you need an anti siphon for the return?

[Moonstream]

just wondering, because I dont have one, and people seem to like to use them. my return doesnt surrently siphon much, if at all, so Im not sure if that makes it okay not to have one...

[JustinReef]

You don't need one if your sump can hold all the water the return plumbing siphons back after the power is cut or if as you said it really doesn't siphon much water back at all. Your fine without one.

[psteeleb]

without one - the tank could drain to the point where the the return is open in the water. so if it's 3" below the surface, it could syphon to 3" below the surface. the anti syphon hole just provides an air inlet that's higher then the return point so it breaks the syphon before it gets there. If you have a sump that can handle the extra drainage- it really isn't an issue.

the key to success is be able to capture everything that can drain in the event of a power outage or valve getting stuck open. HTH

[Mr..Tang]

The reason is if the power goes off, you won't drain all your water from your display tank into your sump more than likely causing a flood

[Moonstream]

okay, thanks! I have always made sure that I can hold the siphon from the return as well. and as I mentioned, my return currently siphons very little water.