Question for you engineering lot

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Profpointy

Legendary Member
I think it would work. My hazy recollection / dodgy logic suggests the water is pushed up the hose by the air pressure on the surface of the pond, and that would overcome the tendency of the hose to flatten.

I could be wrong - but I'd bet the price of a pint.
 
OP
OP
fatblokish

fatblokish

Guru
Location
In bath
Can I ask why you empty the pond so often?
Sure, it's a small pond, just visible behind the children in this photo and about 3 m3 in volume.
images?q=tbn:ANd9GcSw0ZKWayXTPGdb6On0TviP3ExxM290P7syCTK1tiK2jM1hdPjU8Q.jpg

During the summer months, the ducks that use it (I realise they are chickens in the photo :smile: make a real mess of and in it. We get eutrophication in the pond and it so begins to pong with all the anaerobic activity.
 

welsh dragon

Thanks but no thanks. I think I'll pass.
Sure, it's a small pond, just visible behind the children in this photo and about 3 m3 in volume.
images?q=tbn:ANd9GcSw0ZKWayXTPGdb6On0TviP3ExxM290P7syCTK1tiK2jM1hdPjU8Q.jpg

During the summer months, the ducks that use it (I realise they are chickens in the photo :smile: make a real mess of and in it. We get eutrophication in the pond and it so begins to pong with all the anaerobic activity.


Ah yes I see now. Ducks make a god awful mess of a pond, as we found.
 

slowmotion

Quite dreadful
Location
lost somewhere
I think it would work. My hazy recollection / dodgy logic suggests the water is pushed up the hose by the air pressure on the surface of the pond, and that would overcome the tendency of the hose to flatten.

I could be wrong - but I'd bet the price of a pint.
I don't think so. Here's my dodgy guess.....

Water doesn't spontaneously decide to rise up the vertical inlet pipe. It get's drawn there by the action of water flowing down the outlet section of the vertical pipe. Bernoulli's Theorem of something. The inlet vertical section is therefore under negative pressure and will collapse unless it has rigid walls.

By the way, I'll have a pint of Stella Artois. Thank you.
 

snorri

Legendary Member
I would be thinking of burying a pipe between a drain point fitted in the bottom of the tank and the discharge point with tap fitted at some convenient point along the pipeline. Quite a lot of work to fit a drain and excavate a track including through the pond wall, but much easier in the long term than running out a hose every fortnight, monitoring the siphoning, taking in the hose afterwards and storing it away for a couple of weeks.
 
OP
OP
fatblokish

fatblokish

Guru
Location
In bath
I would be thinking of burying a pipe between a drain point fitted in the bottom of the tank and the discharge point with tap fitted at some convenient point along the pipeline. Quite a lot of work to fit a drain and excavate a track including through the pond wall, but much easier in the long term than running out a hose every fortnight, monitoring the siphoning, taking in the hose afterwards and storing it away for a couple of weeks.
Yes, and no. You're right it would be a more robust solution to permanently bury a pipe, and one that I would normally favour, however as the pond is about a metre deep then so must be the trench, at least for the first part, if the pond is to fully empty...this is quite a feat using only manual tools, at least for us non18th C navvies. And the ground is hard and digging a trench by hand is well difficult, especially as it must cross fences and paths. And inevitably the pipe would block with stones thrown in the pond by ducks or kids. Secondly having a buried pipe gives us only one point at which it can empty and the receiving ground would suffer as a result. Sadly I still favour a portable syphon type arrangement.
 
Location
Loch side.
I reckon we could generate a differential head of about 3-4 metres (between the bottom of the pond and the downstream discharge point), about 20m away. The pond's volume is about 3m3. A small bore hosepipe may take quite a while, and be prone to blockages, but it is worth a go. Ta
Ahhh. Larger pond than I thought. The differential head could even be smaller. 500mm would do the trick. But you'll have to be patient.
 

classic33

Leg End Member
Keep both ends if the hose under water will help draw the water over the high point.
Fill the hose, placing a bung/cap on/in either end and removing them only when both are under water gets round the siphoning.
An old sock on the pond end is an effective filter.
 
Can you not use the pipe you have already to fill the pond up?

I agree with above as the pipe is under suction so will collapse if not rigid.

Once a syphon gets going it will shift water at a good rate so a normal hose pipe may be worth a try. Just take it to site full of water and off it goes.

Throwing a fat person in the pond will be quicker though.
 
I see children in the photo, can they not carry buckets? 3000 litres is only 300 buckets worth :okay:. Or as this is a cycling forum perhaps something like this?

Seriously, looks like you have a decent enough fall to syphon the water away. A flat hose almost certainly won't work, well, maybe a bit but it will remain flat and so have a very small cross section for the water flow (I actually had a fire hose out this morning). The hose with the spiral wire coil as suggested above will work, but probably a bit overkill in terms of stiffness, you're not really pulling a vacuum as you would drawing water with a pump. It's also a swine to lay out as it tends to get a 'memory' of how it's coiled up, especially if cold (leaving it out in the sun would help). Starts to get heavy in larger diameters and it's ££s
Unreinforced hose should be fine for what you need - it'll stay stiff enough not to collapse, cheaper and easier to handle. Basically, a big garden hose.
 
Balls to sucking on hoses! Technology exists....
http://www.amazon.co.uk/Kärcher-SDP7000-Submersible-Water-Pump/dp/B0012PVBD2#productDetails

Note that this pump copes with crap. A siphon hose won't.
Good option IF power is available and would be my first choice. OP didn't say there was power (I was assuming there wasn't). And a lay flat discharge hose would work with it too.
Only downside is that particular pump has a float switch to stop it when the water level falls, so won't pump pond out below that level. Unless someone is standing holding the float up or some sort of stick and string arrangement made up for it to hold where it won't shut off as water level falls.

Syphon hose blocking shouldn't really be a problem if a big enough diameter is used. A garden pond seller (oddly enough) should have something suitable and probably better priced than my earlier links. 50mm should do it, don't think it'll be particularly quick even then.
OP says water is available, so to get syphon going. Lay out hose, seal lower end (hand over the end), fill hose with water, put top end into pond, remove hand from lower end. No (ugh) hose sucking required.
 

classic33

Leg End Member
Good option IF power is available and would be my first choice. OP didn't say there was power (I was assuming there wasn't). And a lay flat discharge hose would work with it too.
Only downside is that particular pump has a float switch to stop it when the water level falls, so won't pump pond out below that level. Unless someone is standing holding the float up or some sort of stick and string arrangement made up for it to hold where it won't shut off as water level falls.

Syphon hose blocking shouldn't really be a problem if a big enough diameter is used. A garden pond seller (oddly enough) should have something suitable and probably better priced than my earlier links. 50mm should do it, don't think it'll be particularly quick even then.
OP says water is available, so to get syphon going. Lay out hose, seal lower end (hand over the end), fill hose with water, put top end into pond, remove hand from lower end. No (ugh) hose sucking required.
Seal both ends, prior to placin in the pond, or any water lost will just empty the hose.
 

Globalti

Legendary Member
Lay-flat hose definitely won't work; the weight of the water each side of the "summit" will just suck it flat.

Siphoning is all about the weight of the water contained in the pipe. Take a length of pipe, fill it wth water and make a u shape. The water will remain in it as long as both ends are at the same height but if you lower one end below the water level, water will spill out (this is a useful DIY method of establishing a level around a room). Invert it into a n and in theory the same will happen except that air will probably rush in and the pipe will drain itself. Keep the pipe full and lower one end and the extra weight of the water in that end will overcome the weight of water in the other end and pull it upwards, creating a siphon.
 
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