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Thread: filtration.

  1. #1
    Tosai
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    Red face filtration.

    hey everyone I hope all is well.

    Ok being relatively new at this hobby I think I have read too much too soon and now Im totally confused.

    Regarding filtration most filters have pre filters or settling chambers for the larger part of the poo. This is included in the total surface area of filtration required per cu/ft/mtr of pond water. this is fine if you have a gravity fed filter. But when you have a submersible pump all the refuse is chopped up very fine and therefore does not need a settling chamber, or does it?. What material would you use in this filter and how much. Because I used brushes in my pre filter all the fine refuse went straight through and into the bio filter clogging it up very quick. Can anyone help with how much filter material I need and what stage the differant material is used in.

    I have a pond that has app. 14000ltrs, 16000ltr submersible pump that delivers about 12000ltrs to the filter.

    hope you can help or put me onto a site.

  2. #2
    Daihonmei
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    Hi Tangles,

    And therein lies the problem with putting the fish waste thru a pump first! It is much better to have the waste roll and be gently pulled by gravity to the first chamber. That is way most serious hobbyists opt for gravity flow.
    If you do use a pump at the head of the filter, it is wise to prefilter it with a mechanical first stage before contact with the impeller blades happens.
    There are a couple of ways to do this. The simplest and cheapest way is to have a pefilter on the pump itself and most manufactures have pre-sponge type mechanicals on the intake . Trouble is, in a koi pond, the sponge gets clogged quickly and must be changed and cleaned often- expecially in spring and summer ( the high feeding seasons). I have designed cages around pumps for fellow club members that have slip out pads on all sides so that the pads can be removed easily and new ones installed while you clean the dirty ones and disinfect them. It is slightly less work and the pump tends to always deliver true turn over ( unlike the sponge that slows the turn over down as it gets clogged).

    Another, better way to do this is to install a pond drain to a sump and place your pump off the floor in the sump ( or even near the surface). In an advanced version of this you can have brushes or a filter mat divide in the sump that blocks waste from rising to the pump location/area.

    Many ways to skin this cat! JR

  3. #3
    Daihonmei PapaBear's Avatar
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    And therein lies one of the biggest issues with submersible pumps "in-pond". Because they pulverize the waste to efficiently they interrupt the settlement phase of mechanical filtration which forces fines removal into the typical biochamber. Gravity feed to settlement/mechanical/bio in a long throw system with the submersible at the END of the cambers (post filtration) eliminates that problem and is much more efficient.

    In your case using pressurized bead filters that automatically backflush when they become partially plugged might be the only reasonable way to manage fines, but modifying your system would probably be a more efficient use of your time and money.

    Refresh my memory. How is your pond and filtration plumbed up?

    Looks like JR and I were cross posting.

    "And therein lies the problem"...
    Larry Iles
    Oklahoma

  4. #4
    Daihonmei MikeM's Avatar
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    Quote Originally Posted by Tangles View Post
    ... when you have a submersible pump all the refuse is chopped up very fine and therefore does not need a settling chamber, or does it?
    It does. The problem is that the pulverized waste is very light. As a result, the settlement chamber has to be much larger. The water has to be slowed to a very gentle flow by gravity to the next chamber. There are various chambered filter designs around to help with this, but all require far more space than is usually practical. Until you are in position to re-work your pond to a gravity flow system, the bead filter may be the most practical approach. But, it will need a prefilter to keep out algae glarf. Alternatively, you can try doubling the filters fed by the submersible pump, dividing the flow from the pump so each system gets half the flow. This will slow the water and increase the amount of settlement in the system. It becomes work to maintain such a filtration system. The same energy put into converting to a gravity flow system will result in less work.

  5. #5
    MCA
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    Honmei MCA's Avatar
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    Also from a "green" perspective, submersible pumps are more a whiter shade of pale. They typically use more watts for the same gallons pumps push compared to an external centrifical pumps such as from brands like Wave, Sequence, Evolution, and many others. Bottom line, pump first only if there is no other choice.

  6. #6
    Jumbo RobF's Avatar
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    There is no solution like the right solution which is to use bottom drains to a settling chamber from the start. Everybody who has built a koi pond knows this, unfortunately 4out 5 first timers don’t get this, since our minds are elsewhere. So we adapt and adjust what we’ve built, until we build pond #2. Mike and the Old Cat Skinner have given you good advice. It doesn’t sound like you are using a bead filter, but one (such as an Ultima II) will filter out most of the pulverized mechanical waste, but you may have to backflush it often (maybe every other day).

    It might work (do I hear a yeah verily, or a no way!?) you could buy (or build) an in pond bottom drain (or 2), as opposed to a through the liner type of pond drain, and gravity flow it to a settling chamber where you have relocated your submersible. For gravity flow at the rate you mention 12000 lph (and depending upon the distance from pond to chamber) you would need a pipe(s) with a significant diameter.

  7. #7
    Daihonmei
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    The distance from the drain to the sump should not be too long nor should the pipe be too wide or the entire route will become a settlement chamber of it's own. Some of the old timers have seen build up ( actually biofilm mounting over organic material that has settled out) close off as much as 60% of the pipe's throat. In time, this becomes an incubator for aeromonas/pseudomonas production. In a more evolved version of this dynamic concern, experienced pond designers have placed a flush T in line just before the sump itself so as to create an open pressure drop in order to drain the build up in the line. It is truly remarkable to see what that T will pull out in the way of foul brown water when moments before the water seemed clear when entering in the sump. - JR

  8. #8
    Tosai
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    OH THE TRIALS AND TRIBULATIONS OF US MERE MORTALS, THANK YOU ALL FOR YOUR SUGGESTIONS. i HAVE JUST BUILT A TEMPORARY PRE-FILTER CONSISTING OF BOTTOM INLET FROM THE PUMP, VOID OF APPROXIMATELY 50 LTRS, THEN A MESH AND ABOVE THIS PEA GRAVEL OF ABOUT 65 LTRS. I REALISE THAT THIS WILL NEED A BACKFLUSH AT VERY REGULAR INTERVALS BUT THE BABIES ARE WORTH THE TIME AND EFFORT. NOW AFTER READING YOUR COMMENTS i THINK IT MIGHT BE A CASE OF TOO LITTLE TOO LATE. SO i THANK THE LOCAL KOI OUTLETS WHO FIRST SOLD ME ON THE IDEA OF A SUBMERSIBLE IN THE POND.

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