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Thread: UV vs. Better Mechanical Filtration

  1. #1
    Nisai Motown's Avatar
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    Question UV vs. Better Mechanical Filtration

    It's a bad weather day and the board is a little light today, so I'll pose this question to all.

    Have we all become to dependant on UV to keep our water clear?

    I ask this because the only advantage of algae in a pond is to utilize (lockup) organics from the water. The algae then could be filtered out of the water by a good mechanical filter. (I know, most pond filters don't do a good job with unicelled algae) When the algae was removed, the organics went with it. Now, we use UV lights to mutate the genetic structure of the algae so it can not reproduce. Thus leaving more organics behind for the biological filter (bio-reactor). The result is larger biological filters to handle the excess load. If you live in temperate climate, this can be handled with a Bakki shower and larger pump. In the north, we use an expensive nexus product.

    I always thought the key to the nexus was the ability to mechanically screen the unicellular algae.

    So here is the question:

    Is it better to improve the level of mechanical filtration (beyond current standards) vs buying and OVERSIZED UV light system?

    Motown

  2. #2
    Honmei KoiCop's Avatar
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    Quote Originally Posted by Motown View Post
    I ask this because the only advantage of algae in a pond is to utilize (lockup) organics from the water. The algae then could be filtered out of the water by a good mechanical filter. (I know, most pond filters don't do a good job with unicelled algae) When the algae was removed, the organics went with it. Now, we use UV lights to mutate the genetic structure of the algae so it can not reproduce. Thus leaving more organics behind for the biological filter (bio-reactor). The result is larger biological filters to handle the excess load. If you live in temperate climate, this can be handled with a Bakki shower and larger pump. In the north, we use an expensive nexus product.
    Hello Motown . . .

    There are a couple of givens you seem to have skipped over?

    In a mature koi pond which has been properly designed, stocked, fed, filtered and maintained, green water should only be a short blip on the radar screen during Spring -- if it occurs at all. If it lasts longer than a couple of weeks, then these are some of the issues that need to be dealt with.

    In any case, a properly sized UV system can prevent the algal bloom from developing in the first place so there's no large load of dead algae to be removed.

    Finally, it's the settlement and mechanical stages of our filtration systems that remove the organic debris from the water column -- not the bio-filtration.

    Best wishes,
    Don Chandler
    Member: AKCA, ZNA, KoiUSA

  3. #3
    Nisai
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    Quote Originally Posted by KoiCop View Post
    Hello Motown . . .

    There are a couple of givens you seem to have skipped over?

    In a mature koi pond which has been properly designed, stocked, fed, filtered and maintained, green water should only be a short blip on the radar screen during Spring -- if it occurs at all. If it lasts longer than a couple of weeks, then these are some of the issues that need to be dealt with.

    In any case, a properly sized UV system can prevent the algal bloom from developing in the first place so there's no large load of dead algae to be removed.

    Finally, it's the settlement and mechanical stages of our filtration systems that remove the organic debris from the water column -- not the bio-filtration.

    Best wishes,
    Do you know of a pond with full or near full sun that can do without a UV and maintain gin clear water? I have not heard of such a thing.

  4. #4
    Nisai Motown's Avatar
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    Don, I agree about the bloom during the late spring.

    My point was more about the low level of unicellualr algae that reside in the pond. The stuff that you can hardly see, or in such small amounts you don't notice it until you put a 40 micron (1/4 human hair diameter) bag filter on your discharge. I will put a bag ($4) on the discharge of my pond before I have a party, the water goes from really clear to cristal clear in a couple of hours. When I do this, I estimate that I'm removing 2-3 pounds of unicellular algae that can not be seen.

    I agree with the UV, I just haven't understood why people feel that the investing in two 55-70 watts UV lights is a good return on their money.

    I see people in our club who have two UV lights, but skimp on water changes to save money.

  5. #5
    Nisai Motown's Avatar
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    Quote Originally Posted by hacnp View Post
    Do you know of a pond with full or near full sun that can do without a UV and maintain gin clear water? I have not heard of such a thing.
    hacnp,

    I'm not saying don't do UV lights (I use one myself). I'm just saying algae is good, it locks up nutients in the water, then you can filter out the algae. UV lights tend to hide a water quality problem. CLEAR water does not equal CLEAN water.

    The point of the post is to suggest that we need to spend more time on mechanical filtration instead of expanding our existing UV systems.

    motown

  6. #6
    Daihonmei PapaBear's Avatar
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    It kind of goes back to Steve C's "Its a System" argument. The majority of the time in a mature pond that is properly designed it really is the blip on the radar Don refers to. The reason for the blip is the momentary uptick in nutrients while the biofilters play catch up.

    Whether you use UV or not, mechanical removal of the physical cells of algae is the same. Dead or Alive, it must be physically removed. If it is physically removed in its green state the nutrients that fed it are removed as well. If the algae has been broken down by UV the cell walls will rupture and nutrients within will be released back into the water column to feed a new bloom. Pick your poison, but one way or the other the same stuff has to be dealth with.
    Larry Iles
    Oklahoma

  7. #7
    Honmei KoiCop's Avatar
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    Quote Originally Posted by hacnp View Post
    Do you know of a pond with full or near full sun that can do without a UV and maintain gin clear water? I have not heard of such a thing.
    Hello Ken . . .

    'Fraid we're the wrong folks to ask about that, with as many shade sails (4) as we run on our pond.

    Maybe someone who has far greater knowledge about koi ponds around the world can answer that.

    Anyone seen JR recently?

    Best wishes,

  8. #8
    Nisai Motown's Avatar
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    Thanks Larry,

    But doesn't UV light effect the DNA so that the algae can no longer reproduce? I don't think it kills the algae directly.

  9. #9
    Honmei KoiCop's Avatar
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    Point well taken, Larry.

    Motown . . .

    Guess I just don't see UV $$$'s competing with Mechanical $$$'s -- at least not in our case.

    We've done 3 major mechanical filtration upgrades (added a 2nd skimmer/pump/Ultima II circuit, doubled size of settlement, added Cetus Sieve) while we're still running the original 80W UV installed when our 6K pond was built back in 2004.

    So maybe we agree after all?

  10. #10
    Nisai Motown's Avatar
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    Larry, I can't argue with your system, it's top notch both in mechanical and UV.

    I was taliking more about the lower end of the spectrum, people with 3-4000 gal ponds with two UV units, and mechanical filtration that doesn't seem to match. I'm starting to see a movement here in the midwest to have UV lights and biological filtration (bio-reactor) with little or no mechanical filtration. When I ask at the pond stores (already know the answer) they tell me that mechanical filtration is "old school" and really not needed anymore. Kaldnes and UV, skimmer basket, thats all you need.

    What micron screen are you runnin on your Cetus Sieve. I believe they have a couple of options on the screen size.

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