My (almost) finalised Pond Design. Need feedback on filter!
  • hypersushihypersushi May 21
    Posts: 20
    Hi guys,

    Have a look at my koi pond design. It is supposed to be a river flow system. Dimensions 9ft (W) x 13ft (L) x 4ft (D). Shallowest end is 3ft, deepest end is 4 ft. Aim is to keep 9 jumbo kois and have goldfishes and plants in the planter box. Pond will be shaded. Plan to keep it gravity-fed with as little protruding pipes as possible. I have one protruding pipe for possible trickle tower should the filtration be inadequate. My main concern is the filter. In the past, the up-down partitions have worked for many koi enthusiast but now, new technology has come. I want to incorporate stainless steel sieve (DIY) which I plant to rinse every day and also do daily flushing for filter BDs ( as much as needed to water my plants and nothing more).

    1. See point "A" of filter (hand drawn). How high can it be? I want to to be a high as possible to incorporate the sieve. Will 1 inch gap between the partition and the wood deck be too close for comfort?

    2. See point "B". Is there a recommended angle between A and B so that water covers almost all the surface of the sieve rather than a big gush of water hitting one section of the sieve?

    3. For last chamber (pump chamber) is assisted by float valve to top up water. Are there any instances where the water might drop too low that the float valve cannot equalise the water in time, causing the pump to burn?

    Really would appreciate your feedback. Have visited some koi kichi's homes but I am still a total newbie when it comes to koi filtration.
  • hypersushihypersushi May 21
    Posts: 20
    BTW, the horizontal flow thingy is following ERIC style filtration
  • Md+FahamiMd Fahami May 23
    Posts: 32
    This is superb bro.
    You must have put a lot of thought and time designing this.
    Hope can see the final product or the development.

  • harryyewharryyew May 24
    Posts: 396
    Greetings hypersushi....

    (1) Your hydraulic design will not work as you have perceived. The height of your proposed partitions need to be determine based on the Total Energy Water Level ( TEL) and the Hydraulic Water after losses of energy as the water flow from chamber to chamber.

    (2) With the proposed pond size..... 9 jumbo size koi not realistic. if they do get into jumbo.... at best 3 kois.

    (3) Filteration system should be designed such that you will not be enslaved to the daily maintenance needs. Initial startup you will have the enthusiasm. Imagine 1 or 2 years down the line.

    (4) Your dry chamber too narrow.

    (5) The constricted partition gap.... nothing much to gain except the flow velocity at that particular point will increase.....You change laminar flow into a turbulent flow.

    (6) Look at your drawing ref: WA0001, water level at chamber 2, 3 and 4 will be at the same level. Assuming you have allowed for adequate openings for continuity of flow.

    (7) Pump chamber... too small....

    (8) Point A water level will be about same height of your main pond water line level.... if will be approximately 25mm lower based on what you have allowed.

    (9) Point A- B sieve...useless.... make no difference it is placed before or after point B. Imagine the sieve entrapped with fibers or weeds or leaves etc...

    (10) Point C-D.... if you have designed it right hydraulically...... Point C-D sieve... nothing to clean..... therefore unnecessary consideration.

    (11) Bottom drain discharge right... So filtration base level should be lower than main pond base level by say 25mm to 50mm.... That is if you have to drain the main pond dry for whatever reason later.... else not important.

    (12) Your dry chamber is to allocate the standpipes or to install a outfall discharge pump to external drain? Its depth dependable on how you intend to use it for and the thickness of the concrete base of your filtration pond.

    No go... bro....


  • hypersushihypersushi May 25
    Posts: 20
    Thanks bro Harry for your comments. This is what I am looking for before I make a very costly investment. Few people have told me the second sieve is unnecessary.

    1) What size do you propose for dry chamber and pump chamber?

    2) Not understanding what you mean the A-B sieve is useless. I take it you are not a fan of sieves? or the way I designed it is useless? How can I improve it?
  • harryyewharryyew May 26
    Posts: 396
    You are welcome bro hypersushi

    The size of the dry chamber depends on what you are putting there... you need to allow for a person to gain access to repair whatever you want to place there.

    The sieve you proposed from Point A to Point B, no need if your 1st chamber settling chamber has been design efficiently. The stainless steel sieve (DIY) can be replaced with just a J mat and it will serve your need. You need to understand the Continuity of Flow design to maintain Laminar Flow and to ensure the flow rate is not restricted or change due to access denied. Q1A1 = Q2A2 where Q1 = Discharge at point 1, A1, cross section area at point A where the flow pass thru, Q2 and a2 will be the same thing at point 2. As water flow from point 1 to point 2, there will energy losses which cause the water level to drop or lower than point 1.

    To determine the changes in the hydraulic energy level, you can use Bernoulli's principal to guide you to determine. Unless you have some reference pond design which you know the hydraulic is working fine to your expectation then... you can copy it and need not have to calculate all these to satisfy yourself before a full startup.

    Sieve can be used but not in the manner your have conceptualised... thus prompting me to remark it as useless. By the time the water reached 3rd chamber you should hardly have much fine and the pump chamber the fines are practically zero and only little bit will be accumulated after a year which 30 second flush should have it clean off the base.

    Your concept and consideration is made without a full appreciation of the engineering and hydraulic behaviour of the fluid as it travels from chamber to chamber and also the functional and maintenance issue so that you can relax your cleaning activities to maybe 3 times a year if and when it is necessary. I clean 2 times a year. Spent half a day each time and everything jalan....

    IMHO, the way you design it , is at its infant stage. You also need to design to ensure the water will be crystal clear and how the chlorine from the tap water can be removed etc. Are you planning to use UV light for sterilisation of the return water?

    On the pump chamber, it will depend on what sort of water return per hour you want.

    Remember, the surface area of the biological filter medias is dependant with respect to the food you feed to the koi. and the pump return flow rate is dependant on the ambient amount of ammonia and and nitrite and etc you want to have at any one time in the system assuming under a steady flow situation.

    Again pump chamber should allow you to gain access to change the pump with ease. 800mm x 800mm minimum but go for around 900mm x 900mmm. You should consider to have at least 2 pumps (1 standby and 1 duty and say change over every 6 hours or 12 hours). So in the event the pump is downed, you no need to panic and take your time to have it repaired or replaced.

    You have to redesign your whole pond system else you will regret and become enslave to your pond on its maintenance.


  • harryyewharryyew May 26
    Posts: 396
    You cannot beat the water flow into submission, you must learn how to take its current (which you input into it) and work to your advantages....
  • HDCuHDCu May 30
    Posts: 1,117
    Bro Hypersushui,


    Let me start by saying that your design is NOT an Eric system and in fact far from it. It is more of an up and down filter design. An eRic filter design does not have chamber and only one drain to flush all from brush and bio areas and its design to clean the bio in much less time than your design. Eric design works in only horizontal flow with aeration in between filter media sets. It is usually design to be maximum depth of just less than 70cm while rated speed of pump should fall in the range of 4 or more minutes of settlement time to work most effectively.

    Second you have many areas like planter box and down and up falls that will eventually collect waste that need to shipon or flushed if there are drains. These will collect waste.

    Third, you can grow jumbo koi with that dimension which is more or less same surface area as my smaller pond. I have grown jumbo gosanke in the smaller pond before and I know of fellow hobbyist that have smaller surface area that have grown jumbo as well. Do take note that while the koi may still grow to jumbo size their movement will be limited because of the smaller surface area.

    Fourth, removing waste is before it decomposes is necessary and so is ample water change to the better health and growth of the koi. You will avoid problems such as dropsy, parasites, ulcers, stagnant growth, drying of skin, etc when you take care of the filters and do enough water change.

    Fifth, seives blocks easily as compares to brushes which handles string algaes well. In Eric system, regardless whether waste pass thru the brushes does not matter since flushing removes it. If your filter space is 1m x 4.2 meters in length, you can just divide the into two sets of filters of 0.45m of width x 4.2 meters. each filter set needs to sloped where the end part where the pump(maximum of 5000 gph) is located is higher by 200mm as compared to the bottom drain pipe area before the brushes. If possible make a spray pipe ample pressure located at near the pump directed towards the brush side. This will ensure that once you flush the drain pipe, open the spray pipe at the other side to totally clean the whole filter chamber. Once or twice a week system maintenance with water change will be my recommendation. You can couple the eric system directly to a bakki shower with media for more aeration and better nitrate control. You dont need any return pipe in the walls of the pond because it serves no purpose based on my experience and in fact can create nitrogen buildup in the water. Returns would be better coming from above to surface in the opinion. Current in the pond and water homogenity is handled thru aeration.

    Good luck
    Post edited by HDCu at 2017-05-30 12:18:36 am
  • hypersushihypersushi June 7
    Posts: 20
    Bro HDCu,

    Thanks for your honest and good advice. I am a little confused about your last statement that water returns from the walls of the pond (underneath my planter box) is useless and will in fact contribute to nitrogen buildup. Mind explaining how is that so?

    Wouldn't having water flows in bottom wall and the (almost) upper walls be useful? bottom ones will shoot the fish waste into the BDs and upper ones cause some flow of water where the planter box's water blades flow cannot reach?
  • HDCuHDCu June 7
    Posts: 1,117
    Bro Hypersushi,

    If you put a japanese airhose beneath the planter box, there will be a soft current that will push the downward flow of water from the planter box or bakki to the edge of the pond. Water will circulate.

    I am against the use of TPR and wall pond returns in small ponds because

    1. its not necessary
    2. it creates pressure on the pump making it work harder and thereby can shorten its lifespan as compared when the water is returned above pond surface.
    3. If a strong pump sucks in air continuously and the return is released midwater in a small pond, there is a chance of cavitation of air which compose more of nitrogen causing supersaturation which in the long term may be harmful to the koi.
    4. A strong mid current will attract koi to swim against the current. While this may seem to exercise koi, in my experience the danger does not outweigh the benefits. I know of serious hobbyist that used to push 6700 gallons per hour of pressurize flow in his big pond and he had koi that grew with bent bodies. After removing the strong midflow and directing it all to bakki and allowing just bottom air diffusers to create currents, he didnt have anymore incidence of bent koi.

    With regards to your idea of bottom current pushing waste directly to bottom drain is not a wise idea. I know of a hobbyist that used to have that design. Most of his koi stayed at the bottom instead of freely swimming in the middle of the pond. It was difficult to train his koi to look for floating food. Feeding sinking food requirea that he throw little by little because the current will push the sinking food directly to the bottom drain.
    Post edited by HDCu at 2017-06-07 03:01:44 pm

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