Enough flow to pull full siphon?

azbigjohn · Feb 3, 2017

I am planning out my plumbing for my new tank. Previous owner ran a single return and a single drain in a center overflow. I am afraid to count on a single drain, so I drilled in a new 3/4" return, and will be running a 3/4" return line through a Sicce Synchra 5.0, up to loc-line that will have a single splitter to run two return lines.

That leaves me two 1" bulkheads for drains. What I would ultimately like to accomplish is to run one line as a full siphon with the second as an emergency line, but I do not know if I can dial the drain down enough to maintain a full siphon.

Carried over from my old plumbing I have two 1 1/4" herbie-style drains (that then size down to the 1" bulkhead) that I can extend a couple inches to fit the new tank. I would replace one of the drilled caps with a solid cap, and then put a ball valve below the bulkhead to dial it down. My question is, will that return pump be able to support a full siphon?

Any thoughts on my plumbing? I am limited to the two 1" bulkheads in the overflow, but am open to other ideas/plans if you have any advice...

azbigjohn · Feb 4, 2017

Quick daytime bump to see if anyone has any thoughts on my plumbing question...

Roy 9121 · Feb 4, 2017

Do you have pictures?

azbigjohn · Feb 4, 2017

Roy 9121 said:
Do you have pictures?

No, because I haven't installed anything yet...

I will plumb in a full siphon as I described if it will work, otherwise I might just go with a double Herbie...

azbigjohn · Feb 11, 2017

Well, I finally have pictures, and an answer to my question...

Yes, a 1 1/4" herbie-style drain, through a 1" bulkhead, will get enough flow through a 3/4" return (from a Sicce Synchra 5.0) to support a full siphon, although you will have to throttle the drain down to about half flow...

I should note all the pictures below are using hose-water, as it is also serving as my leak test for my plumbing.

Here is a picture of my dual Herbie-style overflows. The one without the hole in the cap ifs facing forward, and I have a 3" extension down to go far enough down to support the flow. The one with the hole in the cap is the "make-up" flow

Here is the plumbing into the sump. The siphon line is on the left, and you can see I have it cranked way down. After a few minutes of bubbling, it tunes itself to full siphon, and water is barely tumbling down the second line. In this picture it is running full bore, and you can see no bubbles and smooth flow...

I still have some waterfall noise, as I have about 3" of fall down to the waterlevel in the overflow, but it isn't bad at all.

So, I am happy it worked out. I had already worked out my fallback plan, and knew the two Herbies could more than handle the full flow from the pump (it is what I ran on my last tank) but since this had a single overflow (versus dual corner overflows on my old tank) I wanted to try and quiet it down with a full siphon.