return line depth on a 60G breeder

[Trever]

Let's say my return line sits 1" below the water line in a 60G breeder. By my calculations that means about 7 gallons of water will flow back down to the sump when the pump is off.

Assuming I have the sump capacity, is that a problem?

My previous builds have used an up and over return that immediately breaks siphon when the pump goes off, so minimal drainage back down to the sump. In other words, I have no experience with submerged returns and more significant back flow. Wondering if there is anything I should know?

Note: Please assume I'm dead set against lock line or otherwise putting back pressure on my return pump, and against check valves (even if used in reverse and other tricks), small holes to break a syphon, etc.. I'm just looking to plumb a return line that ends at the bulkhead, water shooting straight out into the tank, but below the surface so it doesn't make noise etc. Obviously, the bulkhead hole (for 1" PVC) also needs to be far enough below the top of the tank glass to preserve structural integrity of the glass.

 

[The Farmer]

If your sump can handle the back flow then you should be fine

 

[jda]

Drill a small siphon break hole in the return just below the water surface. It can be small, but test it to see if it is large enough to stop the siphon. If not, then step it up until it is. Maybe start with 1/16 and work your way up?

Flapper valves work and are more reliable than check valves, but they do get old and people tend to forget about them. If you use one, make sure that you can take it off easy and replace it with some unions.

 

[Snoopy 67]

It really comes down to you sump level when running.
Most sumps run around 1/2 full to allow for a shut down.
Measure the difference when off vs running & that is what you need available + some extra to be sure.