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  1. #1
    Senior Member Rank = Sansai Point's Avatar
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    First pond filtration system

    Hi all,

    first proper post so please be gentle

    I'm in the early stages of designing my first pond. It will be circa 10,000 litres for about a dozen or so small koi, maybe a couple of tench and perhaps a couple of sturgeon/sterlets. It's going to be a pretty simple pond built into the ground with a pond liner, with at least a lily and probably other plants in the pond, with a submersible pump.

    I've inherited a filter tank 600L x 450W x 400H (74L actual water volume) tank which has 11 brushes in and after reading a lot about filter systems I think I'll be building an anoxic system to go with it. I am also thinking of adding a second stage mech filter with various matting between the brushes and the anoxic tank, or if feasible adding the matting on top of the brushes.

    I have a few questions if anyone could help:-

    1. I understand the need for laminar flow across the anoxic baskets but am looking to naturally add more oxygen into the system. I will have a small waterfall (approx. 800-900mm drop) of some sorts from the anoxic chamber back to the pond but can I discharge the outlet of the mech filters above the anoxic tank to create a water fall to the chamber? I could feasibly build in a laminar flow panel (a sheet with holes in it, ) at the intake end of the chamber.

    2. Pump size – if I use a 10,000 lph pump (maybe more) might there be any issues with high flow velocity through the anoxic chamber?

    3. UV – would the best position for a UV light still be before the mech filters as in most systems I’ve seen? If I placed it after the mech filters would the dead algae collect in the anoxic chamber, increasing chamber maintenance (bottom drain), or would maintenance be less than cleaning out the brushes and matting? I just need to build space for a UV as it might not form part of the first build until I see what the water clarity is like.

    Apologies for rambling on a bit and thanks for taking the time to read it if you got this far.

    Cheers.



  2. #2
    Extreme Koi Member Rank = Rokusai peter57's Avatar
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    What’s you budget?
    How much space do you have available for filters?
    How much filter maintenance are you prepared to do (or want to do)?

    Apart from the anoxic angle (great choice ) what you describe is fairly “old school” and will require A LOT of maintenance to keep koi.

    If you haven’t already, I’d suggest you search the forum and read up about bottom drains, skimmers, sieves and especially drums. If you can afford it, and want an easy to maintain pond, these are definitely the way to go.

  3. #3
    Senior Member Rank = Sansai Point's Avatar
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    The pond is going to form part of a complete garden overhaul and my budget is "as cheap as possible". I know that most people on here are avid koi keepers who aim for perfection, and I really do appreciate all the effort they make for that, but I just want a pond that I can start growing a few small koi on for a future, larger, properly budgeted pond.

    I've read about all of the systems you mention but the cost is way more than I can spend at the moment. The pump I've been looking at has 2 inlets so was thinking of adding a skimmer to one of them.

    With regards to maintenance, I understand that I'll be cleaning out the mech filters a couple of times a week in the summer but that's not really a problem for me. I'll be leaving extra space where the filters are going for any future upgrades if I change the setup but this isn't my forever home so don't plan on spending £1000's on filtration at this point for 4-6" koi. The system I proposed, although as you say is mostly old school, falls within my budget.

  4. #4
    Extreme Koi Member Rank = Rokusai peter57's Avatar
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    Quote Originally Posted by Point View Post
    Hi all,
    first proper post so please be gentle

    I'm in the early stages of designing my first pond. It will be circa 10,000 litres for about a dozen or so small koi, maybe a couple of tench and perhaps a couple of sturgeon/sterlets. It's going to be a pretty simple pond built into the ground with a pond liner, with at least a lily and probably other plants in the pond, with a submersible pump.
    That's a decent size, but koi grow quite quickly and produce a lot of waste.
    Still, plenty of ponds are built exactly as you describe and give plenty of pleasure to their owners.

    Quote Originally Posted by Point View Post
    I've inherited a filter tank 600L x 450W x 400H (74L actual water volume) tank which has 11 brushes in and after reading a lot about filter systems I think I'll be building an anoxic system to go with it. I am also thinking of adding a second stage mech filter with various matting between the brushes and the anoxic tank, or if feasible adding the matting on top of the brushes.
    An additional mech filter before the anoxic would be a very good idea.

    Quote Originally Posted by Point View Post
    I have a few questions if anyone could help:-

    1. I understand the need for laminar flow across the anoxic baskets but am looking to naturally add more oxygen into the system. I will have a small waterfall (approx. 800-900mm drop) of some sorts from the anoxic chamber back to the pond but can I discharge the outlet of the mech filters above the anoxic tank to create a water fall to the chamber? I could feasibly build in a laminar flow panel (a sheet with holes in it, ) at the intake end of the chamber.
    As long as the water isn't falling directly onto the baskets you should be fine. That's pretty much how my system works - the water flows by gravity out of my drum into the anoxic chamber. An empty section of the chamber separated by a perforated sheet from the baskets sounds perfect.

    Quote Originally Posted by Point View Post
    2. Pump size – if I use a 10,000 lph pump (maybe more) might there be any issues with high flow velocity through the anoxic chamber?
    As long as your perforated sheet has enough open area the flow will be distributed over a large area (compared to say a 2" pipe) so will be moving much slower than in the pipe.

    Quote Originally Posted by Point View Post
    3. UV – would the best position for a UV light still be before the mech filters as in most systems I’ve seen? If I placed it after the mech filters would the dead algae collect in the anoxic chamber, increasing chamber maintenance (bottom drain), or would maintenance be less than cleaning out the brushes and matting? I just need to build space for a UV as it might not form part of the first build until I see what the water clarity is like.
    The best position for the UV would be after the mech filters, but if you are thinking of an inline unit (as opposed to an amalgam) then it would need to be pump fed.
    Putting the UV before the mech filters would be better than not having a UV, but won't be as effective (because the water passing through contains far more solids at this point).

    Quote Originally Posted by Point View Post
    Apologies for rambling on a bit and thanks for taking the time to read it if you got this far.

    Cheers.
    No apologies needed - better to ask now than after you've built your pond.
    Good luck with the build .

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  6. #5
    Senior Member Rank = Sansai Point's Avatar
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    Peter, thank you!

    You've confirmed my thoughts and I'm happy to hear that I could feed the anoxic chamber via falling water. I will also be adding a 2nd stage filter box for matting.

    Although this is my first pond, I built my first pond nearly 40 years ago at my parents house and it's still going strong. As a kid I also had a small pond of my own with a couple of eels (that I saved from being eaten by the neighbour) that I used to hand feed. I can't begin to guess how many countless hours I spent looking after the fish and enjoying them. That filter system is pretty basic and although it has a mixture of fish there are several koi which are always healthy and happy. I also design piped water systems (as well as any other mechanical building services) for a living so have a pretty good understanding of flow dynamics.

    I'm a lifelong angler so put me anywhere near water with fish in it and I'm a happy bunny.

    Again Peter, many thanks for your help.

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  8. #6
    Senior Member Rank = Sansai Point's Avatar
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    Can anyone advise what sort of size my second filter box, with coarse, medium and fine matting, should be please?

  9. #7
    Senior Member Rank = Gosai Jampot's Avatar
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    Why not check out available sheet sizes of matting and size the tank accordingly to avoid cut waste?

    In a multi bay (which is effectively what you are creating) the depth and breadth of the bays are similar even if the length varies, but that by very little unless there is a vortex for the first bay.

    There is a possibility that a bay with matting will also have a biological effect with a consequent production of nitrite and nitrate to the detriment of the anoxic efficiency. For that reason, I would be inclined to make do with the minimum amount of material in that bay to achieve water clarity.

    Jim
    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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  11. #8
    Senior Member Rank = Sansai Point's Avatar
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    Hi Jampot. My worry is that if the box/surface area of the matting is too small it could create back-pressure that feeds back into the brush tank and causes it to overflow.

    I'm new to all this so the above is only theoretical on my part and perhaps the flow rate through the matting filters is more than I'm guessing, although when dirty the back pressure issue will be amplified. I would have thought there would be an optimum size for the matting filters based on water flow rate. I'm probably going to get a pump rated between 15000-20000lph, which I'm guesstimating would give me about 10-12000lph actual flow through the anoxic chamber and back to the pond.

    Noted about the possible bio effect with the mech filters but not much I can do about that.. I'll be having plants in the anoxic chamber as well so perhaps they might help offset any nitrite and nitrate issues. Might also have a few in the waterfall if I can build in some room for them.

  12. #9
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    I may have missed it but why are you going for brushes ??they do a great job tbf but are a right pain to clean .

    You can always pick these up second hand think I've seen them around 100 notes

    https://www.cotswoldkoi.co.uk/produc...IaAnU9EALw_wcB

    Or if any good at diy there is a brilliant build on the diy bit on the forum .
    Load easier to maintain and no extra nitrate to worry about

    Sent from my SM-N9005 using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

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  14. #10
    Senior Member Rank = Sansai Point's Avatar
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    Quote Originally Posted by Ajm View Post
    I may have missed it but why are you going for brushes ??they do a great job tbf but are a right pain to clean .

    You can always pick these up second hand think I've seen them around 100 notes

    https://www.cotswoldkoi.co.uk/produc...IaAnU9EALw_wcB

    Or if any good at diy there is a brilliant build on the diy bit on the forum .
    Load easier to maintain and no extra nitrate to worry about

    Sent from my SM-N9005 using Tapatalk
    Thanks AJM. I've already got the tank with brushes that was part of my parents pond filter. I quite like the look of that compact sieve though and I might be tempted if I could get one for £100ish. I assume I'd still need filter mats as a 2nd stage.

    i'll take a look at the DIY sieve build

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  16. #11
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    If running the seive and anoxic I don't believe you would need a mat bay tho could be wrong.. Sure you can swop the mesh out for a finer one if needed aswell to help reduce fines

    Sent from my F5121 using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  17. #12
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    https://r.tapatalk.com/shareLink/top...ink_source=app. I now have this sieve and its perfect First pond filtration system

    Sent from my F5121 using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  18. #13
    Senior Member Rank = Sansai Point's Avatar
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    I just read through that thread mate.. can't see why I couldn't make one of those

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  20. #14
    Senior Member Rank = Supreme Champion Ajm's Avatar
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    Quote Originally Posted by Point View Post
    I just read through that thread mate.. can't see why I couldn't make one of those
    It's cracking a cracking job like. Sure John1 would help you out if needed mate

    Sent from my F5121 using Tapatalk
    Freddyboy the legend

    "we are water keepers first"

    Johnathan

  21. #15
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    Quote Originally Posted by Ajm View Post
    It's cracking a cracking job like. Sure John1 would help you out if needed mate
    I've got a few thoughts about modifying the design.. is there a particular reason why the water falls onto the mesh or could it be fed from underneath so the water flows upwards through it?

 

 

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