Nice Cheap DIY Overflow

Discussion in 'I made this!' started by Covey, Feb 4, 2005.

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  1. Dingo

    Dingo Giant Squid

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    no the siphon wont break... the whole point here is to have the most distance between the two. that is what gives you the pressure difference to drive the overflow.

    you can get more than 170gph out of 3/4" of these if you extend the distance, however it is much easier to just bump it up to 1"
     
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  3. webgeek

    webgeek Plankton

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    Clearly I'm doing something wrong. I've lowered the outlet as suggested and it breaks the siphon as soon as the water level in the tank drops below the inlet as I suggested it would. I believe the outlet level combined with the inlet level is what gives the self-priming nature of this system and I wasn't surprised to see it fail with the lowered outlet.

    Additionally, the speed of the flow was unchanged. I think part of the problem there stems from the nature of the u-joint over the top of the tank and how we draw air from the pipe. Using the threaded brass fitting leaves a good bit of dead space in the top of the chamber as it protrudes fairly deep into the pipe. The tighter you screw in the fitting, the more dead space it leaves. I think this combined with how close the siphon outlet is to the water level (less pressure) are causing my unusably low volume.

    -Mike
     
  4. reefmonkey

    reefmonkey Giant Squid

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    [​IMG]

    Here is how both of mine are built. They flow what I expect them too and have never lost siphon.
     
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  5. reefmonkey

    reefmonkey Giant Squid

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    I'm not a hydro expert but I think the problem with you losing siphon is that there isn't anything to hold the water level inside the tube on the intake side of your overflow.

    Also I don't want to disagree with Dingo but when I built my second one I wanted to get the max flow from it and assumed that by putting the tee higher it would draw water fast enough to keep the air out of the system. In fact it was the exact opposite and only by moving the tee lower was I able to get what I wanted for flow.

    Another possible problem for you is the water level inside the tank itself. I don't think you will ever be able to hold enough water in any sized pipe to keep the siphon from breaking.
     
  6. cwar21

    cwar21 Astrea Snail

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    i guess im gonna open this thread again

    i did your design covey but havent did the air check valve yet but i am going to.... is there a way to test it before putting that? i havent glue yet either. i want to make sure its right..

    here r pics
     

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  7. RPM1

    RPM1 Fire Worm

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    I just built one of these the other day because my old skimmer box wasn't keeping up with my pump after I replaced it. Looks like yours but I made a surface skimmer pipe for the intake like in reef monkey's drawing. Works like a champ. I tested mine in the sink with the faucet running over the skimmer pipe. Once primed with the check valve, ran great no loss of prime once started, decent flow considering the lack of water moving into the skimmer with the faucet. Once fired up in the tank I have no complaints.
     
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  9. cwar21

    cwar21 Astrea Snail

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    Hey I guess that's what I need o do first before I test it.... Add the check valve.... Does the out take need to be under water?
     
  10. Donkey

    Donkey Bristle Worm

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  11. cwar21

    cwar21 Astrea Snail

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    Hey thanks for the link...... I really want to see if I can get this one working but I just don't know what steps I'm doing wrong
     
  12. RPM1

    RPM1 Fire Worm

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    You need to pour a cup or so of water in the vent have the intake pipe full as it would be inside the tank and get the air lock out with the check valve. It should then drain whatever water you put into the intake side. When I tested mine I just let the spray from my sink cascade over the intake and it drained whatever went in. Once in the tank it drained whatever I threw at it.