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17-10-2020, 10:42 AM #1
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….
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17-10-2020, 11:42 AM #2
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.2016 new 6000 gallon pond
https://www.koiforum.uk/pond-construc...ghlight=feline
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Manky Sanke Thanked / Liked this Post
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17-10-2020, 12:20 PM #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?
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17-10-2020, 01:29 PM #4
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.
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17-10-2020, 01:30 PM #5
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.2016 new 6000 gallon pond
https://www.koiforum.uk/pond-construc...ghlight=feline
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17-10-2020, 01:31 PM #6
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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17-10-2020, 01:55 PM #7
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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Koiz Thanked / Liked this Post
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17-10-2020, 02:02 PM #8
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Koiz Thanked / Liked this Post
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17-10-2020, 02:40 PM #911,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade
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17-10-2020, 02:47 PM #102016 new 6000 gallon pond
https://www.koiforum.uk/pond-construc...ghlight=feline
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Koiz Thanked / Liked this Post
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17-10-2020, 02:59 PM #11
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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jphamill Thanked / Liked this Post
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17-10-2020, 03:11 PM #12
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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Frimley Koi keeper Thanked / Liked this Post
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17-10-2020, 03:16 PM #13
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Koiz Thanked / Liked this Post
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17-10-2020, 03:18 PM #1411,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade
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Frimley Koi keeper Thanked / Liked this Post
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17-10-2020, 03:24 PM #15
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17-10-2020, 03:37 PM #16Jim jampot !
Imagine, at least 6 other Jampots on Ebay!!!!
Yes, I did rather like to have jam with everything in those days
JimI 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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17-10-2020, 03:55 PM #17
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Koiz Thanked / Liked this Post
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17-10-2020, 04:01 PM #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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17-10-2020, 04:21 PM #19
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" . Would just like to add I have small, cute feet with no fur, but do have fluffy socks with rabbit ears
https://youtu.be/haBOYm9SpDA
Sent from my SM-N910F using Tapatalk11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade
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Frimley Koi keeper Thanked / Liked this Post
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17-10-2020, 04:42 PM #20
Best plants to remove Nitrate
pug has a very impressive veg filter on his pond, have a look at some of his his youtube videos....