Overflow - max flow of siphon

[FSM]

My overflow is still really noisy. The problem is, it sucks in a lot of air (1" drain, quietone 3000 pump @ ~550 gph), so there is lots of turbulence as it flows down to the sump.

I want to convert to something similar to the design described here: http://beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx

There is a second 3/4" hole currently used as the pump return. I want to use this as the primary drain, running it at a full siphon. Then, the 1" drain will be the backup/excess overflow; if the primary gets clogged, the 1" should have no problem handling the full flow.

The problem is, I don't know what the max siphon flow of the 3/4" drain will be. The actual flow rate of the pump will be around 500 GPH after modification, because I'll have to use some more elbows to get the output over the rim of the tank. The sticky says 340 GPH is the max gravitational flow for 3/4", but that doesn't apply to full siphons, I don't think, just traditional overflow drains (not siphons).



thanks

 

[black056mtc]

siphons will handles around 2x of gavity flows +/- on distance /angle and bends etc...

 

[Arthur]

I'm not going to read all that, but try a T on your intake. I've found with back mounted overflows a T is the quietest, or I would suppose a durso with a T would be quite too

 

[cypher1024]

I'm reasonably sure that the 340gallon/hour figure is a full siphon.
You can always put a ball valve on your siphon pipe to choke it down and lower its flow rate if it's flowing too much...

 

[FSM]

I put a ball valve on the 1" drain, at about halfway closed (full siphon) it matches the pump. I'm going to use the smaller drain as the backup.

 

[FSM]

It worked. The 3/4" drain picks up the excess; the only noise now is from the pump.