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Thread: My new pond design

  1. #1
    eds
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    Sansai
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    My new pond design

    Right, I'm about to move house (Monday in fact!) so it's time for a new pond! It's going to be a streamflow design and I'm trying to maximise the efficiency of this while reducing the maintenance so I'm having the uplifts automated at the deep end dumping onto a bog garden by the pond and the filter will be a surface intake straight over a DIY double sieve then pumped onto a shower. The return water from the shower will return via 4, 3" pipes to the shallow end of the pond to set up the circulating water current. Anyway enough talk, here are the plans;

    Plan view,


    Side view,


    End view,


    Side views of the filters,


    It's concrete and block construction in 4" blocks backfilled with concrete rather than on their sides, then insulated and glassed. The whole thing will run on one pipe pump rated at 7,500gph at zero head and around 5,000gph at 2m head (the static head from the sieve water level to the shower spray bar should be 1.7m).
    The pond will be around 5,000 gallons and about 5m by 3m and 2m deep at the shallow end down to 2.5m at the deep end.

    Let me know what you think, any ideas, observations or comments will all be appreciated please.

    I would especially like to hear about whether people think the gravity return pipes will create enough flow to set up the current along the bottom down towards the sumps. I have a couple of people who've offered me advice and their opinions differ! One reckons that the water needs to be pumped back in to get the sweeping flow; the other reckons that a more gentle return will work fine on a pond this size. I can understand that pumped water will have a greater velocity returning to the pond but then each of these 3" return pipes is going to have 1,250gph going through it! Surely that's going to create a fair bit of flow?!

  2. #2
    Nisai
    Join Date
    Sep 2005
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    78

    Positive Gravity Head

    The design looks good to me, I think you will have plenty of current to sweep the bottom.

    However if you find the flow lacking, I notice that your design includes what appears to be a catch basin for your showers. By reducing the diameter of the returns at the point of return to the pond you could create positive head by having the water level rise in that catch basin. This would increase the velocity of the returns as you decrease the diameter. I would suggest female threads inside your returns at the bottom of the pond, you could then just thread in the next size of bushing to go down in diameter of return without any pipe work extending into the pond.

    On our pond I have a gravity return of about 5000 GPH going thru one 4 inch return that is reduced to 2 inchs at the point of return. There is about 30 inches of Positive Head above this return and it creates a good current of about 1 ft. per second in our 17 X 27 ft. oval shaped pond as measured at the perimeter of the pond.

    Regards, Ken

  3. #3
    eds
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    Sansai
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    Cheers Ken for the reply. Was beginning to think either no one was interested or the diagrams weren't very clear - sometimes it's very easy to do a drawing that you understand because you drew it, whereas other people haven't got a clue what the various bits are!!!

    The large final tray will be a fibreglass tray to both act as a catchment hopper for the two stacks of stainless steel trays with BHM in above and will also contain more media (BHM when I can afford more, probably alfagrog until then - I can't seem to source feather rock over here). So it will be easy for me to restrict the flow with a reducing bush without using threaded parts (I can source both metric and imperial parts and then a friend has a lathe to shape them exactly to size to fit into smooth 3" pipe). It'll mean I won't have to have threads as I'm a bit paranoid about having nothing that will collect waste and need cleaning, hence the double sieves straight from the pond via a channel - no gravity fed pipework that will need purging.

    Thanks for the feedback as with trying to have the sieve differently and using the returns to generate the currents it will mean that this pond will run and circulate around once an hour using just 295W (plus an air pump coming on twice a day for about 20 seconds) and should need almost no maintenance aside from flushing the waste off the sieve grills.

  4. #4
    Sansai
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    Michigan, USA
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    New Pond

    I am very intrigued by the design. Is it started yet or still tweaking stage?

    Outdoor I am assuming? If so any difference in the winter filtration/flow?

  5. #5
    eds
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    Sansai
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    Quote Originally Posted by Jake Levi View Post
    I am very intrigued by the design. Is it started yet or still tweaking stage?

    Outdoor I am assuming? If so any difference in the winter filtration/flow?
    Not started yet - I move Monday and am planning to start digging the week after as I'm on my summer holiday from school for the next 5 weeks and I won't get much done once I'm back teaching. While I've had this design pretty much ready to go for a few months, I still keep tweaking and changing bits and I know with past experience that this process will continue all the way through the build stage.

    The principal is that it's a streamflow design so the heavier-than-water debris is washed down towards the uplifts. The uplifts will purge twice a day via a timed air pump.

    It will be outdoors so all the feed to the two sieve elements is via a channel in the shallow end pond wall. This will mean that the floating weirs on the sieve will function as skimmer weirs too. I was keen on this as I find my current skimmer collects an oily build up in the skimmer I have to scoop out and by using the sieve weirs as the only weir that can't build up anywhere but will go through the sieve and be pumped up straight over the shower.

    It won't be heated in the winter but it will have insulated foam under the fibreglass and will be covered to retain the heat. The shower and all the other filters will be in an insulated filterhouse. There will be no change in flow planned for the winter as I don't think the flow is going to be too severe. Fish will be able to rest in the deep end where the flow will be lower. During the winter I won't purge the uplifts as often.

  6. #6
    Sansai
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    Pond design

    I like it, as you say, tweaks to come, looking good,

    how many adults are you planning for it?

  7. #7
    eds
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    Sansai
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    Quote Originally Posted by Jake Levi View Post
    I like it, as you say, tweaks to come, looking good,

    how many adults are you planning for it?
    I'm going to try and be good and only put 25 fish in there but that's going to look very empty! My fish aren't as big as some of the guys on here yet. If they do get to 80cm plus then I might have to put less than that in. At the moment I have about 18 fish that will go in there this year, the rest will stay in their current pond.

    Can you think of any tweaks I might want to consider?

  8. #8
    Daihonmei PapaBear's Avatar
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    I like the fundamentals and I don't see any reason to worry about the return flow not generating current. Volume is Volume is Volume and the flowrate you return will dictate the net velocity across the bottom of the pond.

    I do have a couple of questions though.

    I don't see a skimmer circuit of any kind. Do you plan to have one?
    I also don't see any water returns except those on the bottom. Moving all of the water at the very bottom won't encourage any circulation from top to bottom and vice-versa. It would be petty easy to return a controlled volume of water via mid and near surface returns by using different return line arrangements. Just a thought.
    One other observation. I'm assuming it gets a bit chilly there in the winter and Bakki's will chill the water considerably. Is there any kind of bay filter you can easily switch to for winter operation? Keeping the chill out and the system running can extend your season considerably.
    Larry Iles
    Oklahoma

  9. #9
    eds
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    Quote Originally Posted by PapaBear View Post
    I like the fundamentals and I don't see any reason to worry about the return flow not generating current. Volume is Volume is Volume and the flowrate you return will dictate the net velocity across the bottom of the pond.
    My thoughts too but a friend over here who does know his stuff got me a bit worried saying it might not be a high enough velocity! I think he's wrong though but guess I'm going to have to build it to prove the principle!

    Quote Originally Posted by PapaBear View Post
    I do have a couple of questions though.

    I don't see a skimmer circuit of any kind. Do you plan to have one?
    The sieves are fed by a channel at the water's surface so there isn't a skimmer circuit as such, just a channel in the pond wall. The sieve weirs will then function as skimmer weirs too. All the water coming over the sieves will be fed from this skimmer channel.

    Quote Originally Posted by PapaBear View Post
    I also don't see any water returns except those on the bottom. Moving all of the water at the very bottom won't encourage any circulation from top to bottom and vice-versa. It would be petty easy to return a controlled volume of water via mid and near surface returns by using different return line arrangements. Just a thought.
    I'm planning to put all the returning water along the bottom to get the water to follow the streamflow circulation pattern. This means the water will flow down the slope along the bottom towards the sumps then up the end wall and flow along the top from the deep end towards the skimmer at the shallow end. Water that isn't taken in by the filter will then go down the end wall at the shallow end to meet new returning water at the base of the shallow end.

    My thinking was that that would create a good mixed water column and create good top to bottom as well as end to end circulation. If I do find the far end isn't circulating a lot then I have a back up plan of an air curtain or air stones.

    Quote Originally Posted by PapaBear View Post
    One other observation. I'm assuming it gets a bit chilly there in the winter and Bakki's will chill the water considerably. Is there any kind of bay filter you can easily switch to for winter operation? Keeping the chill out and the system running can extend your season considerably.
    The whole filter system is going to be enclosed in an insulated filter house and I will probably further insulate the shower in the winter too inside this house to stop it chilling the water. I know a few people over here who do similar things with showers inside so that they don't chill the water. I will cover the pond in winter too to save as much heat as possible.

    Thanks for your questions Larry, do you think my ideas will work?

  10. #10
    Daihonmei PapaBear's Avatar
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    People get confused about velocity pretty easily so it's understandable.

    If you want to increase velocity you have two options. You either increase pressure at the return point by using a pressurized nozzle to "jet" the water at the same volume, or you simply increase the flowrate through the same pipe. Reduce the number of pipes carrying the same gross volume and you increase the velocity at the outlet of those pipes, but you change nothing regarding the velocity or flowrate across the bottom of the pond as the "velocity" is only changed at the point of exit.
    Sometimes I think people just get too caught up in semantics and loose sight of reality.

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