Water gully - a little challenge for you

[AJB Temple]

I need to find a way of returning water to a pond from a filter. This needs to fit in aesthetically with a Japanese style garden.

The water will fall by gravity, from a height of about 30 or 40 cm (I can make this pretty much anything within reason by raising the filter outlet) and will then have to cross another pond that is about a metre wide (but 20 metres long) before reaching the required pond about 4 to 5 metres away.

The pond holds 28,000 litres and the water is being turned round at a rate of roughly 12,000 litres an hour. The outlet is gravity fed and hence is ejecting about 3 litres a second. The conventional method is to drop this via a short pipe straight back into the pond. I can't do that because the narrow pond is in the way.

I could run it underground in a conventional way or I could make a stone rill and run it above ground as a narrow stream. The direct route though is directly across the narrow pond and I am visualising a wide timber gutter (which you do see in Japan). The question is how would you design and make a timber gutter that will not leak (as if it does I am gradually stripping water out of the pond) and will handle this flow rate. It must look good - not a bodge up or twee. I can't line it with lead or copper as this is toxic for fish (there will be various fish including Koi).

One solution is a very wide bamboo channel. I have not yet found suitable bamboo. I am fine with rectangular design.

 

[SteveF]

could you line it with pond liner ?

just a thought

Steve

 

[RobinBHM]

Maybe a gutter lining kit?

https://www.rubber4roofs.co.uk/shop/epd ... ning-kits/

 

[CHJ]

I would not try to cross over the other long narrow pond.

To add to the mystique I would run a Rill or large diameter Bamboo feed to an inverted Sump and let it reappear on the other side of the narrow pond in the form of a spring feeding another Rill to the bottom pond.

As long as the underground piping for the sump is of adequate cross section its length and route to avoid the long pond is not relevant other than finding the easiest way around the long pond, I'm assuming you are already having to do underground piping for the upstream feed to filter and fountain/cascade whatever.

Water pouring into the sump would add addition oxygenating potential.

 

[Jelly]

Accepts is one possible material, if you want to make something from PSE to have a very square look.

Alternatively, the ideal way to go "with nature, not against nature" would be to get a small(-ish) elm trunk, saw it in two and hollow it with a curved adze or scorp.

 

[SteveF]

if it is for aesthetics could you conceal a 3" pipe underneath the gutter to take most of the water away so it enters lower pond below water level
but still has the running water appeal

Steve

 

[Woody2Shoes]

Funny you should mention this, I've just been to Great Dixter, where I was fascinated by their timber gutters on the main house - pairs of oak boards, each perhaps 6" wide and about 6' long, joined at right angles along the edge - then lined with lead (probably code 5 or 6 by the looks of it). If necessary, you could use copper/stainless nails to anchor the lead (no piece longer than about 5' to allow for thermal movement). Cheers, W2S

Here's a picture that gives a clue: http://1.bp.blogspot.com/_r4Klv8u2tgU/T ... icolor.jpg

Sorry - just spotted your last point about lead!!! - could you use copper or zinc instead (copper's perfectly safe for people)?

 

[AJB Temple]

Thanks for the input so far guys. I don't want to use butyl as a liner as aesthetically it is not great. I thought copper would be fine but research on Koi websites suggests not.

CHJ, I am intrigued by your idea, but I am not sure what you mean by an inverted sump. Would you mimd explaining a bit more? My original idea was to bury a pressurised filter under a bridge but even at low density fish stocking unfortunately I need a better filtration system (as you will have gathered I know sweet FA about this fish business), hence having to locate it in a bank across the narrow pond. (There are in fact three ponds, totalling about 100,000 litres, and when I have finished they will look like one pond. Only one will contain ornamental fish).

I can't have any above ground tank close to the fish pond. Yes, I am pumping water out of the pond using a submerged pump (ie not a gravity feed) and the water is also being aerated using a separate air pump. There is also high capacity UV. The water is being pumped to the filter through buried pipework and I could return it that way too, which was my original intention, but as it is a gravity return I thought I might as well try to be creative and make a feature out of it. I can make the outlet either visible or hide it under a bridge I will make. The bridge hides one of the divide strips between the three ponds.

The filtration set up will be half hidden in a bank and otherwise hidden by a Japanese style bamboo fence and various planting. 3 litres a second seems to me to be quite a flow rate, but as I have never done this before maybe it is not a big deal.

I could, at a pinch, actually link the long pond into the fish pond and filter them both. That would make the water return a lot easier. I am trying to get an ancient Japanese look.

 

[SteveF]

sounds an interesting project
if u do decide u need any help i would happily come along to help...although u seem to have an idea in your head
i have kept tropicals...not cold water for many years
i even had an outside tropical tank that got into practical fishkeeping (my sad clame to fame)

Steve

 

[CHJ]

Disguise upper sink with rock surround, fit outlet with wire grill and a layer of pebbles to let water bubble up through or spout out into lower pool.

 

[stevep]

Have a look on ukbamboo.com. They sell large diameter bamboo. Quite pleasantly surprised at the prices on there too. Having found that site, I think an overhaul of my pond and filter may be coming on next summer !

 

[Fitzroy]

Do you have a reference for how big a channel, and what fall, you will need? I'm a process engineer by background, and although I've not calculated fluid flow in channel since uni, what I remember is that it is way less efficient than in a closed pipe. 'Efficient' in terms of flow per unit area. I can probs dig out some equations if you needed me to.

F.

 

[AJB Temple]

This is remarkably helpful. CHJ, does it make any difference what the height differential is? (between your two funnels)

Fitzroy, no, that was one of my problems. An equation would be helpful. If I took a straight run, then the water is falling 30 cm over a maximum distance of 5 metres at a rate of up to 3.66 litres a second.

Thanks Steve P. I will take a look.

Edit: having checked on line, the largest diameter bamboo has an external diameter of 5.5 inches. This is similar to a rainwater gutter and I woud be very surprised if that will handle 3 litres a second. My gut feel is I will need a channel getting on for a foot wide and 6 inches deep (external dimensions) to be retentive enough. That said I could split the flow I suppose.

 

[Neil S]

If you build the inverted sump make sure you have some form of easy access built in. It is essentially a u bend water trap from under a sink. It is very possible it will block up with sludge, weed or algae at some point and it will need to be cleaned. If I understand you right this sump will not only be travelling underground but also under another ornamental stream.
Cover the inlet with a metal mesh to stop any stones or bigger items dropping in.

Good luck

-Neil

 

[AJB Temple]

Having looked at the site again today the sump idea does not work. The ponds are in already and routing the pipework in a way which will provide suitable access in case I get a blanketweed blockage is too difficult. I need to keep maintenance to a minimum as the pond is really incidental to this part of the garden.

 

[SteveF]

is there any way to balance height of 2 ponds so u could dump into narrow pond?

Steve

 

[AJB Temple]

Unfortunately not. That would have been the perfect solution as I could have used the long stream shaped pond as a gravel bed filter. However, the ground levels and design are such that the fish pond has to be level with the long one. They are deigned to look like one continuous pond, even though they are three, but I opted to split them for various reasons. one being the sheer volume of water to be handled.

 

[SteveF]

a quick picture
or even a rough sketch showing heights would help

Steve

 

[AJB Temple]

I know. It is dark now. The original question was about a timber gutter and as usual here there is so much expertise that it has broadened out. It will be a day or two now until I can do a picture as work will intervene!