Overflow not fast enough

Discussion in 'General Discussions and Advice' started by pXius, 22 Jun 2012.

  1. pXius

    pXius

    Joined:
    31 Mar 2011
    Posts:
    1,170
    Likes Received:
    22
    Location:
    Weltevreden Park, JHB
    Hey guys/gals,

    As some of you might know I've got Neil's Drop off tank, but I've ran into a bit of a problem, the overflow can't keep up with the return.

    Have a look at this pic and allow me to explain.

    [​IMG]

    The gap here leads into a overflow box and then down to the sump via 50mm PVC. I can adjust the water level in the box using a ball valve.

    As big as the gap might seem, on the final version the gap is only 2cm high.

    When the return is on the water level rises and makes full contact with the underpart of the brace. The result is that I lose surface skimming and My Mp40's can not generate a proper wave, surface skimming being my main concern.

    I need suggestions as to get that gap bigger or something....

    Shoot!
     
    Last edited: 22 Jun 2012
  2. AdS Guest




    to hide all adverts.
  3. mariusmeyer

    mariusmeyer

    Joined:
    7 Jul 2009
    Posts:
    3,054
    Likes Received:
    210
    Location:
    Jukskei Park, JHB
    What is the return pump pushing out? Why not throttle it back via a T-piece and a small ball valve?
     
  4. RiaanP

    RiaanP Moderator

    Joined:
    11 Aug 2008
    Posts:
    23,142
    Likes Received:
    1,228
    Location:
    Centurion
    Why not remove the little small panes on the left and right of the overflow gap?
     
  5. Nur

    Nur Starz

    Joined:
    5 Jan 2011
    Posts:
    1,469
    Likes Received:
    28
    Location:
    Cape Town
    or get a clamp to restrict uplift pump a bit or get a slower pump?
     
  6. Nur

    Nur Starz

    Joined:
    5 Jan 2011
    Posts:
    1,469
    Likes Received:
    28
    Location:
    Cape Town
    sorry i see marius posted something to that effect.
    what happens when u dont read all posts first. :)
     
  7. Albert Terego

    Albert Terego

    Joined:
    19 May 2008
    Posts:
    599
    Likes Received:
    6
    Location:
    Randburg, Johannesburg
    Seems to me your return pump is too strong so all suggestions above are options.

    Does your overflow pipe perhaps have a valve on it which can be opened further to allow water to drain faster?
     
  8. AfricaOffroad

    AfricaOffroad

    Joined:
    12 Mar 2010
    Posts:
    1,696
    Likes Received:
    35
    Location:
    Ballito, KZN
    That overflow is way too narrow.
    Seeing as its made up of a number of vertical pieces of glass, should be easy to cut them out, putting back smaller pieces. Would be easy to double its length.
     
  9. pXius

    pXius Thread Starter

    Joined:
    31 Mar 2011
    Posts:
    1,170
    Likes Received:
    22
    Location:
    Weltevreden Park, JHB
    Return is rates @ 8000L/h but its not close to that after all the bends, its maybe half that now. I really don't want to restrict them further, doing so I'll end up with much more debris settlement. I feel that the overflow is to small anyway...

    Even with the valve opened up full makes no difference as the restriction lies at the overflow.

    @RiaanP and @AfricaOffroad
    That sounds like an idea, wouldn't that however intrude on the integrity of the tank?
     
    Last edited by a moderator: 26 Nov 2015
  10. dallasg

    dallasg Moderator MASA Contributor

    Joined:
    14 Dec 2008
    Posts:
    16,769
    Likes Received:
    582
    Location:
    Sandton
    may i make a stupid suggestion, might work, might not

    you say it goes to the top of the brace, here is my pic
    looking at the overflow from the front in tank
    the red dots are open 20mm tube, they would then join to riser pipes to allow air to go down and increase the flow, open at the top above the water line, then flow to sump as well, they could even join the main overflow



    [​IMG]
     
  11. pXius

    pXius Thread Starter

    Joined:
    31 Mar 2011
    Posts:
    1,170
    Likes Received:
    22
    Location:
    Weltevreden Park, JHB
    Interesting idea, if I understand correctly those pipes would then be in front of the brace inside the tank?
     
  12. dallasg

    dallasg Moderator MASA Contributor

    Joined:
    14 Dec 2008
    Posts:
    16,769
    Likes Received:
    582
    Location:
    Sandton
    On the outside
     
  13. crispin

    crispin

    Joined:
    22 Jan 2008
    Posts:
    12,223
    Likes Received:
    160
    Location:
    Lilliehammer, Norway
    8000l/h is a pretty rapid return pump. I personally would lower that with a new pump (around 5000l/h-3500l/h) and see how the overflow handles then. Easy enough to borrow a return pump tp test anyway.

    I would also open the overflow box a bit, you'd get better surface skimming although you need egg crate or a protection over that overflow chamber or you will most likley loose fish into that box as it is.
     
  14. pXius

    pXius Thread Starter

    Joined:
    31 Mar 2011
    Posts:
    1,170
    Likes Received:
    22
    Location:
    Weltevreden Park, JHB
    My true return is around 4000/lh after bends, I used a OR3500 with clear hose as a test and got similar results.

    I'm moving end of July so tank will be emptied, think I'll open up the overflow a bit as suggested :)

    Thanks guys.
     
Recent Posts

Loading...
Similar Threads - Overflow fast enough Forum Date
Overflow fitting help please Pumps and Waterflow Wednesday at 11:47
Drilling and overflow HELP Beginner Discussions 21 Oct 2016
Can you make a algae scrubber in your overflow? Anything DIY Related 25 Sep 2016
[wtd] Overflow box Wanted 3 Aug 2016
Overflow cover up General Discussions and Advice 2 Aug 2016
Plexiglas overflow Anything DIY Related 19 Jul 2016
[wtd] H2Overflow wanted Wanted 30 Jun 2016