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Thread: UV light, on or off?

  1. #1
    Nisai
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    Nov 2007
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    Hangzhou, China
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    UV light, on or off?

    I have switched off the uv light of one of my two ponds and it has been 15days and now the water looks pretty muddy, as compared to the other pond, and you can hardly see the bottom of the pond. Apart from that, the fish in both ponds all look very healthy. My question is, what is the purpose of the uv light? Is it only to kill the algae and maintain the clarity of the water? Is it recommended to keep the uv light on or does it make no difference, considering the health of the fish and the pond?

    Thanks

  2. #2
    Daihonmei
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    well, I can tell you what a UV pond isn't. It is not to sterilize the water. Koi pond water, in a good , well circulated system, does not need to be sterilized . The strength of the bulbs in most UV units is very low. So it is not for parasite removal either. First, because it isn't powerful enough and second because ectoparasites live ON the koi and even when life stages are present, the odds of all stages going thru the UV are slime to none. So it does not kill parasites. The only bacteria that UVs can kill are those individual cells that actually travel thru the tube. Those would only be free swimming bacteria and not the types that settle and live an 'attached' life on the pond walls, floors and piping. So these free swimming 'wolf pack' species are all typically heterotrophic aerobic species and they can be killed by UV. But they are also species than are capable of reproducing every 20 minutes when conditions and temperatures are right- so good luck getting rid of those with a single tube UV!!

    The ONLY real purpose for a UV in an outdoor koi pond then, is to wear down single celled algae in circulation. This tends to be seasonal need ( on in April, off in June). And only needed in two instances- one is in early spring when the bacteria, which run the pond environment, are not completely up and running and the single cell algae that causes green water, gets a foot hold. In this case, as the number of algae cells explodes, the UV will damage the DNA and cell wall function so that the algae dies. The second instance is a similar dynamic, in very hot weather the bio load plus the drop in oxygen levels come together to make a second opportunity for green cells to wrestle away dominance from the bacteria populations for a time, especially if circulation is modest and sun is strong. In this case, the flip of a switch will have the UV acting as an ally of the biofilm to beat the green cells back to just so much 'background noise'.

    JR

  3. #3
    Oyagoi gcuss's Avatar
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    Quote Originally Posted by JasPR View Post

    The ONLY real purpose for a UV in an outdoor koi pond then, is to wear down single celled algae in circulation. This tends to be seasonal need ( on in April, off in June). And only needed in two instances- one is in early spring when the bacteria, which run the pond environment, are not completely up and running and the single cell algae that causes green water, gets a foot hold. In this case, as the number of algae cells explodes, the UV will damage the DNA and cell wall function so that the algae dies. The second instance is a similar dynamic, in very hot weather the bio load plus the drop in oxygen levels come together to make a second opportunity for green cells to wrestle away dominance from the bacteria populations for a time, especially if circulation is modest and sun is strong. In this case, the flip of a switch will have the UV acting as an ally of the biofilm to beat the green cells back to just so much 'background noise'.

    JR

    Would the regular use of a good calcium bentonite clay also serve this purpose? I haven't started up my UV yet this year, and hoped to avoid it. I've been using clay. So far, green water, but the fish don't mind, and neither do I and after a brief discussion with my favourite kohaku, we thought we'd give the clay some more time, and see what happens. Am I headed down a slippery slope? I have tons of air in my pond, so I don't think I need to worry about O2, any other concerns with the green water? PH is stable, which I attribute to the clay and daily water changes.

    Thanks,

    Grant

  4. #4
    Daihonmei
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    Good Morning Grant,
    Clay has it’s place for sure, but I don’t think I’d use it to combat green water. Green water itself is a good thing. But it is a ‘tiger by the tail’ as it can easily take over and if it dies, which is likely at some point, it can quickly create a dooms day scenario for your system as it overwhelms it with toxins and all the things that follow a crashing ecosystem ( disease and parasites to name two).
    Clay can be used to pull out of suspension, certain organic components. But this is not why most advanced keeps use it. They use it to provide mineral content to soft or moderately hard water and to bring ALL READY great water to even a higher level of purity via flocculation.
    Using clay as a band aid is never the answer. In that case, you really want to review WHY you are seeing green water. If it is:
    1) seasonal- that is OK and you can use the UV there.
    2) new pond syndrome- it is Ok and time will correct things. You can help the situation by doing small frequent water changes and by not feeding too often or too much. The key is to keep the organic content low so the ammonia during new pond syndrome is only what is coming from the koi’s gills and not decay of organic materials. You will reach ‘equilibrium’ between daily waste nutrient and growing biofilm much quicker this way.
    3) if the circulation/turnover rate is poor, the stocking too high , the filter too small, the water changes too infrequent and the feeding is out of control,- that is NOT OK and these things must be addressed first before looking to clays, PP, ozone or even UVs.
    JR

  5. #5
    Oyagoi gcuss's Avatar
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    Thanks for the response JR.

    I think I'm dealing with new pond syndrome and spring time start up. My pond wasn't completed until Oct last year, and although I had some pond mutts in there for the winter, they were never fed. I'm assuming that because the pond never got above 50 degrees until this spring, new pond syndrome is still a factor.

    I haven't switched on the UV's because I was afraid of a big organic dump with immature filters and such. My plan was to continue doing daily water changes (5% or so) along with weekly maintenance for an additional 10% along with the maturing of the filters and utilizing clay to slowly increase water clarity. So far it's been improving slowly, but I'm in no rush. Up from near zero to about 2' of visibility. As stated my water parameters are great and I thought the fish actually benefitted from the green water. I believe the only drawback to the lack of visibility is monitoring the fish for health problems. But so far, when feeding I look really closely at them and all is well.

    My stocking level is quite good I believe so shouldn't have trouble there. (7 fish in the 6" - 10" range and one that is 14" or so in 6000 gals.) 400 gal settlement An Easy, plus a DIY 100 gals static K1, and a DIY 100 gal moving bed for filtration and Jap mat as a final polisher in the spillway I built. (couple circuits here, not just one)

    Am I headed for trouble and should possibly turn on one UV to accelerate the clearing of the water?

    This is my first spring with a pond and fish I care about, and I don't want have things blow up in my face if I can avoid it.

    Thanks,

    Grant

  6. #6
    Daihonmei
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    right, new pond syndrome . You can't have spring start up problems on a pond in new pond syndrome as there is nothing to 'start up'. Often on ponding boards you will see people chime in with all short of start up short cuts for people just starting a new pond. This is fruitless as those ideas all assume there is an complete established set of bacteria and an adapted supporting cast already.

    You plan shows OK, but I would avoid feeding more than three times a week for now. At some point you will overdo it with clay as no more will be able to be held in suspension at some point with only 5% water changes. I like the 5% water changes so keep an eye on how much clay you add or soon it will become the clarity problem and not a solution. Best of luck, JR

  7. #7
    Lee
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    Sansai
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    As usual, there is always a thread related to something I am interested in myself...

    Hi All,

    re: UV lighting!

    I find that this Spring/Summer I am already having to increase the wattage, as well as, the number of UV lights which I have been using in my ponds.

    Yes, of course, they're all in good repair and I do a constant tube replacement too...all the same it has become apparent this season - what was adaquate in the past is no longer adaquate!

    My friends, it seems to me that we are truly experiencing global warming in my part of the world -possibly in yours as well?

    The increase in algae which which I see my ponds now producing (is more than they have previously produced and the wattage and lights are on 24/7).

    However, regardless of all of my UV lights (all of which are 'on' 24/7 together) they are inadaquate inkeeping up with my ponds production of algae.

    Of course, my feeding is under control. As are my water changes. And, the size of the fish and quantity is kept relative to the size of my ponds gallonage.

    Yes, everything is equal to the past. And, there is nothing new...except, what I can see is that my thermometers are evidencing warmer water. And, the algae bloom is corresponding to this water water by breeding faster than ever before.

    Only a few moments ago I had to again clean an Answer filter screen which I had cleaned off of a thick covering of algae only a few hours earlier.

    Thus, with no alternative I know of ~ I am going to purchase new UV lights, more UV lights with much greater wattage...to get (and, keep) this new problem under control.

    Therefore, for anyone who believes that they may continue to operate their pond this coming Summer without UV lights...you may try, however, I personally do NOT think it is going to be possible. In fact, I doubt it shall even be probable.

    As one hobbyist to another, if I were you, I would be encouraging you to now be purchasing and changing all of your UV light bulbs, as well as, considering the purchase of larger wattage UV lights!

    With my sincerest respect and hugs,

    Lee
    Grand Cayman

  8. #8
    Daihonmei
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    lee, how old are the bulbs in your UV?

    Your pal from New Jersey, JR

  9. #9
    Fry
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    Lee, maybe the reson you are cleaning everything IS the UV. Its killing and floculating the Algea and hence its collectinmg in your filters. If you had less UV it would kill less and most would stay suspended in the water and get through the filters and although it would take a bit longer to clear the pond you wouldnt have to clean so often

    As for Global warming, the IPSCC have admitted the planet has cooled since 1998 by 0.2 C

  10. #10
    Lee
    Lee is offline
    Sansai
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    In reply, Jim...

    Jim,

    One of the UV lights was installed 'new' just this morning!

    Indeed, my friend Jim - I am quite aware that the 'life' of these darn lights is terribly brief. And, irregardless of which manufacturer of UV light promises that their lights are 'longer lasting' I am aware that most have an effective operating light life of less than nine months.

    And, the fact that a newbie might be able to see that there is light still being emitted from out of his/her UV light - it is not indicative that the UV light is still properly functioning.

    Jim, I believe a 100% efficiency factor (for nine months) is not really accurate anyway - as I'd 'guess' most UV lights do not remain 100% percent effective beyond a five month term life...much less their published and advertised life of a full nine months.

    And, as for whatever scientific resource had quoted that we are not experiencing global warming, they clearly have not seen the increased death of our coral which is bleaching white - and, which is a well known direct result of warmer water and the increased biological effect that this warmer water has on our coral. Nor, has this scientific resource read of the projected increase in this years potential number of hurricanes in our region either - which is also well known known as a 'very' direct result of a warmer ocean current and a warmer water base and surface sea temperature.

    Nor, obviously has this highly regarded scientific office taken a personal look at my own temperature gauge which I have taking daily readings of my pond temperature ...which are also reading a higher temperature than in previous years.

    Thus, whilst I respect your choice of sharing this information, I don't know where these knowlegeable scientists are obtaining their information nor where they are looking at their measurements. Nor, where their data comes from?

    My own data comes from a distance of no greater than twenty meters distance from where I am not sited. And, I cannot argue with what I can see...nor, what I have reported above.

    As regards the many life forms of green algae and my pond filtration being able to clear the pond of such debris - let me report back to you in a couple weeks when my new UV lights arrive and are installed; as to the accuracy of your thoughts on this subject.

    I can say without doubt, from my own first hand experience. The result of this recent (algae growth) is obvious. However, if I am incorrect, I shall gladly share my experience with you...

    All the best,

    Lee
    Grand Cayman

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