New pond design

[Davej]

Hi Ed

Well it proved a bit more tricky than I thought!! With the slide valve on the open the gulping of air made anything accurate pretty difficult.

Best estimate was with 1 16000L/h over it at (5' head) - less than an inch, with 2 pumps - two inches and with 3 - four-five inches.

Dave

[eds]

Thank you very much Dave, that's brilliant as it backs up the calculations I did and lets me know that 4, 3" pipes should have almost zero head. Hope I didn't inconvenience you too much. Thanks again.

[Jon W]

Hi Ed

Do you know anyone else who has used pipes straight from the bakki without a pump? When I've looked at all the other examples of streamflow ponds they also seem to have returns at the base of the pond which are powered by pumps and using 1 1/2" or 2" pipework to ensure sufficient flow to move waster down to the deep.

I like the idea of using the 3" pipes because I am trying to minimise the number of pumps I'm using (I'm already up to a minimum of 4 with skimmers and supplementary filtration). Oh, and it just so happens the pond is being dug tomorrow! Gulp! I couldn't wait any longer because the guy doing the digging can either do it this weekend or I will have to wait till January. I feel a bit twitchy that I haven't finalised the design.

Cheers

Jon

[eds]

Hi Jon,
I know people who return from a bakki with a gravity pipe like Dave who posted above, but I don't know anyone using it to set up the current in a pond like I've planned! I've posted on Bito in the states too and the general consensus on there was that it would work well but I think my design is the first to use it in this way - I'd be happy to hear if it isn't if I'm wrong!

I know Stuart T found that the waste moved down to the sumps on his pond even when he only had the shower running and his is sited on the top of the pond walls with a conventional weir. I am 90% sure the design will work.

I do have two back up plans if I find it inadequate. The first is to put reducers in the pipes where they enter the pond to reduce them to 2". This will increase the velocity and will make the water level slightly higher in the final shower tray. The second option is to put air stones or a curtain in the deep end to help get the upwards current there and help get the right current pattern.

I'm in a similar situation to you as Iafter this week I've got 4 weeks of summer holiday left and I really need to get the blockwork finished by then! Got get moving on it next week! I'm just remeasuring the new garden and tweaking the design as I've got slightly different dimensions and an annoying manhole cover where I was going to site the greenhouse growing on pond!

[Jon W]

Hi Ed

I really hope it does work - because I'm thinking of doing the same. I heard of people having the returns down about 12" under the waterline but not necessarily with a streamflow design. I did think of putting in a couple of bottom drains as well but I think these would either impair the streamflow effect or harbour dead water if they're not regularly purged. I seem to remember Stuart finding that the air curtain (your backup plan 2) saying that he found the air curtain tended to lift the waste out of the sump area because it was creating too great a circular current, but I have heard of others being able to use them to great effect. I suspect however well designed the pond it is going to require a certain amount of tweaking to get optimal removal of solids.

Blimey - 4 weeks to the blocking! I'm lucky if I get more than 4 hours in a weekend. Are you able to get a digger to dig the whole - that will save quite a bit of time and pain! Is it not possible to incorporate the manhole cover into the design of the growing on pond so that you have your waste water pipework immediately adjacent to the pond?

Cheers

Jon

[eds]

Unfortunately the manhole cover is in completely the wrong place and it's not a big garden. When I first saw the house it was the location I liked and the garden was just big enough for the two ponds and a nice jungly patio. I'll take some photos tomorrow to show you guys and maybe you can come up with some better ideas. I don't need the manhole as I won't be putting any water to the sewer at all, it will all go onto the garden, mainly onto a gunnera!

The plan was for the QT to be a streamflow type too but 4 foot deep (two feet above ground and 2 feet dug out below) with a 4" bottom drain feeding a cetus and then pumping over a shower. The shower will be designed to drop the water down vertically at the shallow end creating the circular current down towards the bottom drain. This will have an air curtain at the deep end to really get the water churning around. I'm hoping I can turn the greenhouse the other way round to get it to fit but it'll be much more intrusive in the garden then.

You're dead right about Stuart finding an air curtain picked up all the waste but I figure if the flow isn't enough to get the current working then an air curtain might not cause that on my pond if the current isn't strong enough. Al runs two airstones in the corners of the deepn end of his pond so maybe that will be an option. As you said it'll need some tweaking to get the best results.

By the way the depth the water's returned to won;t make any difference. Returning 2" down is the same as 2 foot or 10 feet!

The plan is to start digging and moving stuff around to give me the space next week. I've also got a tree to remove!!! I will get a bobcat in to do most of the digging as my drive is round the back of the garden so there's brilliant access. As I'm on holiday at the moment it does mean I can work 7 days a week on it though, but only until I do back to school in September! Hence having to get the block, and brickwork done by then! Insulating and fibreglassing can be done over a weekend or two I reckon.

[Jon W]

Hi Ed

Here is a Gunnera that I have at the end of my current pond waste pipe.



It was a small lump of unpromising root when I put it in 3 years ago. It's now over 8 foot tall.

Here's the site for the pond;


Digger arrived this morning.


First trench almost dug;


I'm looking far happier than I feel - no proper plan and not sure if I've dug enough long enough for the filter house.


I'll probably start a pond build thread once things are a little more advanced.

Cheers
Jon

[eds]

Now Jon that's a proper pond!!!! And garden! I've moved into a house near the centre of West Bridgford so have had to compromise on the garden - my pond's going to be about a third of the garden! And I'm hoping the gunnera will fill quite a lot of the rest of it! Very jealous mate!

Think you should start the pond build thread now with the before pictures to keep us all updated. I'll be starting mine next week with the current pictures of the garden and the adapted plans I'm still working on.

[Jon W]

Hi Ed

The dig also includes the filter house so it won't all be pond! Couldn't afford to run anything that big. Should be 20' x 10' x 6'-7' sloped depth. I've left about 20' for the filter house. I live out in the middle of nowwhere so the one thing I've got is lots of garden - 3 acres in total. Sitting in a terraced house in London with 12'x40' and with absolutely no idea of the amount of work involved it seemed like a good idea - the plan was to grow lots of vegetables and keep livestock; I hadn't reckoned with the impact the crappy 4K gal koi pond that came with the house would have.

I've started compiling pictures for a thread. I'll be very interested to see how yours goes as well because I think we're thinking along similar lines for the design.

Cheers

Jon

[eds]

Sounds like heaven that Jon! I'm in a suburban 7m by 10m garden and squeezing two ponds in! Sounds like it'll be two more streamflow threads both happening at the same time - should be interesting to see how both of them turn out!

[Jon W]

Hi Ed

Living out here is very much swings and roundabouts - lots of peace and quiet but can't get a decent Chinese takeaway! Here is the finished dig;



Only problem is I think I've dug too deep for the filter room by about 3'. Progress will probably slow to a snail's pace from now on as I can only really work on the pond at weekends. You'll probably have yours up and running before I've finished blocking.

Cheers

Jon

[Jon W]

Hi Ed

Talked to Darren at A4Koi who uses showers on his main pond. His preferred method for returns is to have spigots in the bottom tray of the shower which are attached to the return pipework. The bottom tray is 3 ft above water level and the returns are no more than 2ft below water level. He reckons that there could be problems with backing up if have a sump before the pipework and the returns at pond bottom level.

I'm now thinking that I might use pipework to return the showers but use the returns from supplementary filtration (probably bead filters or Nexus) at the pond base.

The other thing I was wondering if it would be possible to create a scaled down test system to prove whether the 3" returns method would work.

Cheers

Jon

[eds]

Hi Jon,
Another person has suggested that to me but to be honest, and there's no easy way to say this, but they're wrong! The depth of the return makes no difference at all. Deep gravity returns will function exactly the same as a shallower one - the only difference in performance can come from using small diameter pipe which will increase the frictional head. The static head will be exactly the same. Think about it, this is just like a bottom drain in reverse, or a bottom drain coming in at the base of a vortex rather than at the top of it. The depth the pipe is at makes no difference at all because, as you add water into the pipe, the weight of that water simply pushes the water out the bottom. That process occurs irrespective of depth. There is no 'pressure' effect caused by the depth.

If you raise the showers higher then what you do is increase the head the pump has to work to increasing the pumping cost. Also see DaveJ's post about gurgling and bubbling noise from his showers. He has had to add a valve to restrict the flow and create a couple of inches of water in the bottom of his shower to stop it! Simply lowering the bottom tray will give this same effect and keep the head down!

I agree this method is experimental but it follows the principles of water flow and head. There is no need to create a head to 'push' the water back into the pond; it's working just like a bottom drain in reverse and gravity flow into the filter doesn't need this head to function. And I know how much current moving through my vortex sets up the circular current so I'm getting more and more confident my design will work exactly as planned.

EDIT: Forgot to say you will get problems with the flow backing up if your pipework isn't sized properly to allow the flow rate under gravity flow conditions. That's why I spent some time working out how many and what size pipes I would need and am using 4, 3" pipes to return my circa 5,000gph flow rate.

[eds]

Forgot to say as well a scale model would be good, but don't forget that scale models in fluids don't give totally realistic results because you get problems with relatively large boundary layers in smaller pipes which increase their frictional head out of scale to the pipe's diameter. I feel my own model coming on though made out of a washing up bowl with 4 smaller pipes and a trough! I reckon a ferrero roche tub would work well!!!

[oldgit]

hi
Guys great reading as im also thinking of doing the same.i cannot sit the shower outside so im thinking of placing in the filter shed above the vortex.only about six inches above water line. i was going to put a 3inch pipe in the btm of shower then return it to the pond at least 12inches down.
my worry is will the pressure of pond water not go back up the pipe to find its own level as the return from the shower is not pump fed?
i also thought you may be able to tap into the return pipe work using a sweeping tee so the pumped water rushes pass the tee thus allowing the shower water to fall into the faster flowing water.
does that sound like it could work?
keep the bulid pics coming .
darren

ps sorry if ive butted in on the post