DIY PVC overfloy built...but getting weird behaviour (PICS)

Discussion in 'New To The Hobby' started by bigclick_dean, Apr 18, 2009.

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  1. bigclick_dean

    bigclick_dean Astrea Snail

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    Location:
    NSW, Australia
    DIY PVC overflow built...but getting weird behaviour (PICS)

    Hey All,

    I have been plumbing my new tank setup this weekend and built a PVC overflow.

    When I suck air out of the pipe above the "T" and cap it straight away the overflow works a charm (with a bit of a gurgling noise). But when I remove the cap the siphon just drains and stops working.

    I was under the impression that this pipe had to remain open to breathe...

    Is this true? and if so why would my overflow only work when I have it capped and the air sucked out?

    Here are some pics of it.

    Cheers,
    Dean
     

    Attached Files:

    Last edited: Apr 18, 2009
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  3. janderson2k

    janderson2k Flamingo Tongue

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    Not an expert here - but whats that extra length of tube with the cap on it for? I know that overflows should restart once "power is returned". If you stop power and start up again does it continue to work as normal on its own?
     
  4. mjc440

    mjc440 Astrea Snail

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    It needs to be capped because as the water flows empties into the sump the pipe has a "choice" of whether to fill with water or air. If you leave the cap open-it can fill with air. I have a similar setup and it works well with a cap. You can actually tighten/loosen the cap to let some air flow in to adjust the water level.
     
  5. janderson2k

    janderson2k Flamingo Tongue

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    There ya go.. I thought it had to do with suction or something.
     
  6. bigclick_dean

    bigclick_dean Astrea Snail

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    Thanks for all your responses, with a little bit of playing I managed to get it to work with the cap off (just changed some pipe lengths).

    When the power went off the prime was lost so upon return the overflow wouldn't work.

    Now I just need to adjust my inlet height to ensure that my sump doesn't overflow when power is lost (right now when power is lost it rises to about 1mm from the top, too close for me!).

    I will repost some pics of the working model in a bit.

    Cheers,
    Dean
     
    1 person likes this.
  7. Siddique

    Siddique Dragon Wrasse

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    I didn't see this thread till now. If I saw it earlier, I would have told you to adjust the lengths of some pieces. Of course, adjusting the length could lead to overflowing in the sump like you mentioned. I love to work with PVC and one great piece that you can add to your PVC overflow is a ball valve. This way, you can adjust the flow whenever you like. Also you wouldn't have needed to adjust the length.
    Cheers
     
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  9. trent51593

    trent51593 Coral Banded Shrimp

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    ok i have made one of these with no problems and what im seeing is in picture 3, the part that goes over the side of the tank needs a hole drilled in it on top with a check valve so you can suck the air out of the tube to start your flow.
     
  10. bigclick_dean

    bigclick_dean Astrea Snail

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    I have since put a check valve in, although it was working fine for 24 hours with no check valve...It cant hurt though.

    If you have a look over at my "I made this" thread (http://www.3reef.com/forums/i-made/my-homemade-stand-sump-setup-63618.html) you will see that I have ball valves on my return and overflow pipes. You can also see how I have used clear tubing as a union/inspection for the pipes.

    Cheers,
    Dean