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  1. #1
    Junior Member Rank = Fry Number 8's Avatar
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    Which direction should a return pipe face?

    Hold in your mind a cylinder of water 12 feet wide and 7 feet deep. How should an inch and a half return pipe enter the cylinder (water delivered by a Sequence 12000 pump)?

    First, above or below water level?

    If below, which direction should the return pipe face? You have a half sphere of angles to choose from.

    I ask this question because in South Staffordshire there’s a lock called The Bratch, and when operating produces the most-scary whirlpool, and I don’t want one of those….



  2. #2
    Moderator Rank = Supreme Champion Feline's Avatar
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    You would only get a massive whirlpool if the flow was huge.
    I personally don’t think it matters what angle your pipe enters- if there is a bottom drain then there will be a gradual circling of water towards it (direction depend on if you are in the northern or Southern Hemisphere).

    Mid returns are most useful for koi ponds, you don’t have to worry about a cooling effect in winter. But if this is an indoor grow on tank then you might consider an above surface return which is certainly what they do in Japan when fish are brought into the concrete ponds for the winter. It’s noisy though.

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  4. #3
    I thought the Northern and Southern hemisphere theory had been proved to be a bit of a myth? Although there is some truth in it as apparently the water draining direction is more to do with pipe work when it comes to ponds? I'm sure there was a video on here a while ago proving it can drain in either direction no matter where you are in the world?

    If you've got pumped returns on the surface or mid water pushing the water in the opposite direction to the natural Northern or Southern hemisphere direction then surely it would have to change direction before it reached the bottom drain which might be quite difficult to do as you'll have potentially several tons of water spinning one way then stopping and changing direction in quite a small area? Or would you just end up with various mini whirlpools where your returns are and then the water would circulate the correct way for where you are as it goes down the bottom drain?

  5. #4
    Senior Member Rank = Yonsai jphamill's Avatar
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    Coriolis effect or Ferrel's law is no myth you can see it in any sink drain. Moving things not attached to the ground will naturally want go right in the northern hemisphere left in the southern hemisphere and any way they want at the equator !
    That's why similar weather systems are reversed on opposite sides of the globe. I was on a Rugby tour a few decades ago and did actually peer into plug holes in Zimbabwe and South Africa to check this myself ! Even if you swirl it the opposite way, it will settle back to going the way it should.

    Quote Originally Posted by Frimley Koi keeper View Post
    I thought the Northern and Southern hemisphere theory had been proved to be a bit of a myth? Although there is some truth in it as apparently the water draining direction is more to do with pipe work when it comes to ponds? I'm sure there was a video on here a while ago proving it can drain in either direction no matter where you are in the world?

    If you've got pumped returns on the surface or mid water pushing the water in the opposite direction to the natural Northern or Southern hemisphere direction then surely it would have to change direction before it reached the bottom drain which might be quite difficult to do as you'll have potentially several tons of water spinning one way then stopping and changing direction in quite a small area? Or would you just end up with various mini whirlpools where your returns are and then the water would circulate the correct way for where you are as it goes down the bottom drain?

  6. #5
    Moderator Rank = Supreme Champion Feline's Avatar
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    I’ve tested the Coriolis plug hole theory when in Australia for myself and it is true, water genuinely does go the opposite way down the plug hole

    Whether it will do this in an actual pond will depend on loads of factors. I had a circular pond with a return at 90 degrees and it did go anti-clockwise towards the BD as you would expect.
    It wouldn’t take much disruption of flow by a return pointing the opposite way to override this though.

  7. #6
    Member Rank = Sansai Jampot's Avatar
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    I don't think there are any hard and fast rules - 2 very experienced members here already posted without actually answering the question:-)

    Assuming a single central bottom drain in this cylindrical pond I would install returns pointing to the right as you look across the pond, at mid water and just below the surface (assuming a skimmer is installed somewhere) and put a valve on the upper one(s) so it(they) can be turned off in winter along with the skimmer.

    IMHO, YMMV etc

    Jim

    Feline posted while I was typing.....
    Last edited by Jampot; 17-10-2020 at 01:33 PM.
    I don't keep fish, I keep water. I don't keep fish, I keep water. I don't keep fish I kee........

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  9. #7
    Senior Member Rank = Yonsai jphamill's Avatar
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    Ok ok Here is the answer....

    Ponds and baths are really too small to be significantly affected by this particularly when we pump water around them or our feet interfere with the water going down the plug hole !

    Interestingly though you are called Jim and had a user name jampot, my parents used to call me Jim jampot !

    I now must google YMMV

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  11. #8
    Senior Member Rank = Yonsai jphamill's Avatar
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    YMMV

    I like that !

    Quote Originally Posted by Jampot View Post
    I don't think there are any hard and fast rules - 2 very experienced members here already posted without actually answering the question:-)

    Assuming a single central bottom drain in this cylindrical pond I would install returns pointing to the right as you look across the pond, at mid water and just below the surface (assuming a skimmer is installed somewhere) and put a valve on the upper one(s) so it(they) can be turned off in winter along with the skimmer.

    IMHO, YMMV etc

    Jim

    Feline posted while I was typing.....

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  13. #9
    Senior Member Rank = Hassai Koiz's Avatar
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    Quote Originally Posted by jphamill View Post
    YMMV

    I like that !

    Hehe - me too! (I had to look it up an' all Which direction should a return pipe face?)

    Sent from my SM-N910F using Tapatalk
    11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade

  14. #10
    Moderator Rank = Supreme Champion Feline's Avatar
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    I avoid using too many acronyms on here in case ppls don’t know them IYSWIM

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  16. #11
    Quote Originally Posted by Feline View Post
    I’ve tested the Coriolis plug hole theory when in Australia for myself and it is true, water genuinely does go the opposite way down the plug hole

    Whether it will do this in an actual pond will depend on loads of factors. I had a circular pond with a return at 90 degrees and it did go anti-clockwise towards the BD as you would expect.
    It wouldn’t take much disruption of flow by a return pointing the opposite way to override this though.
    Yes my reply was kind of contradicting myself a bit as I agree that water goes down plug holes in particular directions depending where you are and if you get it to go the opposite direction then pull the plug out you can see it stop spinning then spin the correct way again. But in ponds it can go either way depending on the direction of the greatest flow.

    I'm not disputing the Coriolis plug hole theory BTW.

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  18. #12
    Senior Member Rank = Hassai Koiz's Avatar
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    Quote Originally Posted by Feline View Post
    I avoid using too many acronyms on here in case ppls don’t know them IYSWIM
    FWIW, AFAIK, YAR. MWHID Which direction should a return pipe face?

    (Edit: hahaha bl@@dy predictive text messed up my acronym - now corrected - talk about ruin the joke! Which direction should a return pipe face?Which direction should a return pipe face?)

    Sent from my SM-N910F using Tapatalk
    Last edited by Koiz; 17-10-2020 at 04:25 PM.
    11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade

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  20. #13
    Quote Originally Posted by Koiz View Post
    FWIT, AFAIK, YAR. MWHID Which direction should a return pipe face?

    Sent from my SM-N910F using Tapatalk
    BTW it sounds like a SNAFU or a FUBAR coming up ASAP TTFN

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  22. #14
    Senior Member Rank = Hassai Koiz's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    BTW it sounds like a SNAFU or a FUBAR coming up ASAP TTFN
    Which direction should a return pipe face?

    Sent from my SM-N910F using Tapatalk
    11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade

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  24. #15
    I heard the other day that Prince Philip ends his texts to the Queen - OXFORD UNITED

  25. #16
    Member Rank = Sansai Jampot's Avatar
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    Jim jampot !
    Jampot was a cruel (in my mind anyway) nick name at primary school. The first time I ever needed a 'screen name' it came to mind, and if available I have used it ever since. Imagine my surprise when Ebay said it was taken and would I like Jampot 7.

    Imagine, at least 6 other Jampots on Ebay!!!!

    Yes, I did rather like to have jam with everything in those days

    Jim
    I don't keep fish, I keep water. I don't keep fish, I keep water. I don't keep fish I kee........

  26. #17
    Quote Originally Posted by Jampot View Post
    Jampot was a cruel (in my mind anyway) nick name at primary school. The first time I ever needed a 'screen name' it came to mind, and if available I have used it ever since. Imagine my surprise when Ebay said it was taken and would I like Jampot 7.

    Imagine, at least 6 other Jampots on Ebay!!!!

    Yes, I did rather like to have jam with everything in those days

    Jim
    I'd settle for jampots as there are far worse types of pots to be called LOL

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  28. #18
    I think the thread title Which direction should a return pipe face? should be renamed as Which direction will this threads go off in next?

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  30. #19
    Senior Member Rank = Hassai Koiz's Avatar
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    Quote Originally Posted by Frimley Koi keeper View Post
    I think the thread title Which direction should a return pipe face? should be renamed as Which direction will this threads go off in next?
    Well ... it wouldn't seem right if I didn't help the hijack along, so in keeping with the theme of nicknames and acronyms, one of hubs' pet names for me is FBF - Fluffy Bunny Feet (homage to Hot Shots) - which is not just a polite way of saying "hobbit foot" Which direction should a return pipe face?. Would just like to add I have small, cute feet with no fur, but do have fluffy socks with rabbit ears Which direction should a return pipe face?

    https://youtu.be/haBOYm9SpDA


    Sent from my SM-N910F using Tapatalk
    11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade

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  32. #20
    Quote Originally Posted by Koiz View Post
    Well ... it wouldn't seem right if I didn't help the hijack along, so in keeping with the theme of nicknames and acronyms, one of hubs' pet names for me is FBF - Fluffy Bunny Feet (homage to Hot Shots) - which is not just a polite way of saying "hobbit foot" Which direction should a return pipe face?. Would just like to add I have small, cute feet with no fur, but do have fluffy socks with rabbit ears Which direction should a return pipe face?

    https://youtu.be/haBOYm9SpDA


    Sent from my SM-N910F using Tapatalk
    Reminds me of a customer of mine LOL I reckon she was a Hobbit as she was under 5ft tall but the trainers she was wearing looked like they were men's size 12s They were bloody massive

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