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  1. #1
    Senior Member carrhd's Avatar
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    My $2 no break overflow siphon.

    My old siphon is finished. It had been glued into the top of the overflow I built about 15 years ago but about 5 years ago I broke off the top (for a reason that I can't remember) so the siphon was all pitted and had a piece broken out. I covered it with a band of silicone and put it in service.

    The problem that I've always had with siphons in overflows is that when you get the water moving at a good pace little bubbles end up being sucked into the siphon and eventually form a bubble big enough to break the siphon. I overcame the problem by drilling a hole on the downstream side of the middle of the siphon and used a powerhead to suck water out of the siphon constantly. Any little bubbles that find their way into the siphon are pulled out by the powerhead.

    Today Anita, Lily, and I went to Ottawa to pick up drugs and drop off bio balls and I got the parts for my new siphon at Home Depot. I bought a 10' roll of vinyl hose for less than $20 all in. I brought it home and cut a length about the same length as my existing siphon using my $15 Chinese cleaver from Lee Valley. I then poked a hole in the hose about 6/10 of the way along its length and cut a 1/2 inch piece of rigid air tube from my skimmer.

    See the next message for the conclusion...

    Hank.

  2. #2
    Senior Member carrhd's Avatar
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    My $2 no break overflow siphon. (Continued)

    The hold I drilled in the hose was really just a conical hole I poked through the hose with the point of a spade type drill bit. I had a bit of trouble pushing the little piece of rigid air tube through but did manage. I then used a pair of kitchen shears (don't tell Anita) to cut saw teeth in both ends of the hose. This is to prevent the hose from making a tight seal with the bottom of the overflor on either end.

    I am using a Hagan 201 powerhead. I cut the intake filter cone off and stuffed in a nylon nipple the right size for air hose.

    Once it was all finished I installed it in the overflow (which I built with the same 1/8" plastic sheet I used to build the protein skimmers), hooked up the protein skimmer with a 1 foot piece of air hose, and turned the power head on. It works great!

    Hank.

  3. #3
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    Great Job Carrhd hyeah:

    I have 1 question. WHere you have the powerhead line to the siphon tube to prevent a break and I'm guessing to start it up after a power outtage... DO you loose flow since some of it flows through the powerhead ?

  4. #4
    Senior Member Deafboy's Avatar
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    Quote Originally Posted by carrhd
    The hold I drilled in the hose was really just a conical hole...
    Did you use an adhesive to hold the small tubing?
    20 g reef, 72 g reef

  5. #5
    Senior Member carrhd's Avatar
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    Quote Originally Posted by mp123
    Great Job Carrhd hyeah:

    I have 1 question. WHere you have the powerhead line to the siphon tube to prevent a break and I'm guessing to start it up after a power outtage... DO you loose flow since some of it flows through the powerhead ?
    I don't lose any flow as a result of the powerhead robbing water from the siphon. The siphon has to remove all of the water that my pump is pumping in so it just moves a tiny bit more water to make up for the loss to the power head. It wouldn't be a problem unless your pump was putting so much water into the tank that the siphon was barely able to keep up. Then, you're courting disaster anyway.

    Hank.

  6. #6
    Senior Member carrhd's Avatar
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    Quote Originally Posted by Deafboy
    Did you use an adhesive to hold the small tubing?
    Nope. I reamed out the hole that I jammed the tube into WAY smaller than the tube diameter then pushed the tube against the surface of a cutting block to stuff it into the hole. It's tough to get anything to stick to vinyl so I used a pressure fit. No nails required.

    If you were really worried about the tube popping out I guess we could modify my gum and shoestring design to include a screw in pipe nipple with a flange that would be inserted from the inside out (like a tiny bulkhead fitting) and bolted in from the outside.

    Hank.

  7. #7
    Senior Member Dazz's Avatar
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    I would be worried about any siphon that uses a powerhead to keep working. There have been many cases on many boards over the years stating the precarious nature of siphon overflows that use a venturi of some type to keep the U-tube free of bubbles. If the power ever fails or it stops working, you may end up with a wet floor. Do searches on RC and you will find more than a few accounts of people having their siphon break.

    I think the reason you had a big bubble form in your U-tube was because you didnt have enough flow going through it for it's size. If the water is moving fast enough, the bubbles never get a chance to stay at the top. You could try a smaller diameter of tubing for the U-tube or you could try a higher flow pump.

    I had a lifereef overflow that didnt use a powerhead and I never saw bubbles forming at the top.
    -Dazz

  8. #8
    Senior Member carrhd's Avatar
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    You're probably right, Dazz. This is an annex tank so I don't haev a big pump on it, just a powerhead. My overflow includes a baffle on the drain side (outside the tank) to maintain water around the bottom of the siphon. That way, when the power goes off the water stays in the siphon. If the siphon ever gets broken it takes the powerhead about 30 seconds to get it going again (which is a long time given that I use a 701 at the main pump for the clown tank.) This is really just a stop gap measure until I get another 25 and drill it.

    I didn't add to my first post a recommendation to everyone NOT to use a siphon type overflow. Lee Valley sells diamond hole saws which with a bit of oil do a nice job of cutting clean holes through glass. If you're going to setup a small tank you can consider drilling it yourself. If you're setting up a big tank haev your glass professionally drilled to your specifications.

    Hank.

  9. #9
    Senior Member Dazz's Avatar
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    Ahhh ok makes sense now
    Nice job anyway.

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