Is UV lights really necessary in a outdoor koi pond setup?
  • HDCuHDCu July 2012
    Posts: 1,086

    Ultraviolet radiation was discovered to be a safe and effective solution for killing microorganisms. The findings resulted in the use of UV radiation as a viable method to treat drinking water. UV's are now used by most Koi pond owners for protozoan sterilization and killing of water bourn algae. The UV light zaps the DNA of the algae as it passes through the U.V. light chamber and either damaging it or killing it from within.

    All koi hobbyist have heard about this even the novice ones. However, is it really necessary and most importantly is it really "safe"?

    The last time I used a UV light was more than four years ago and for my present new pond I dont intend to place one as well. I have been asked by several hobbyist why when a UV light is an "indispensable tool" to have crystal clear water and "kill" harmful bacteria.

    Here are my opinions why I dont think UV is necessary.
    1. UV light gives a sense of complacency to some hobbyist thinking that crystal clear water means healthy water. The fact is that UV light does not remove nitrate, phosphate and dissolve organic compound build up. In fact, by applying very high wattage of UV, you destroy the algae that will eat up these fertilizers. If you dont do enough water change then these "fertilizer" will just continue to build up to the point that if your UV light is unable to cope up, expect a green pond. I have seen crystal clear pond with UV lights but the kois skin looked rough and they looked lethargic while I have seen kois intentionally placed in green pond when lifted showed amazing skin quality and growth.
    2. Green water can actually be controlled and crystal clear water can be achieved by partly shading the pond, and most importantly controlling the nitrate, phospate, and dissolved organic through water change and culturing enough good bacteria in filters that can hold them.
    3. UV radiation is a radiation that may reduce bacterial count but it does NOT choose the good or the bad bacterial population. UV as per some studies conducted cannot kill some bacteria also and maybe mutagenic to some bacteria. In any pond system, it is not healthy to sterilize the water but what is necessary is to maintain a healthy pond environment where both good cultured aerobic and anaerobic bacteria are dominant and coexist to protect kois from dangerous bad bacteria that may multiply.
    4. There is also the issue of cost. I have computed the cost of operating a UV including semiannual bulb replacement as well electricity cost and compared it to the cost of water change(luckily water here is still cheap) and determined that the difference is manageable considering water change has the added benefit of diluting the toxins in the pond water.

    It is definitely harder to achieve clear water without employing UV but it is not an impossibility.

    If you wish to add more to this topic, feel free to comment.
  • ShukriShukri July 2012
    Posts: 4,870
    Bro HDCu,
    There is truth in what you have said as I too have done studies, and my conclusions are similar to yours. Green way is not a problem to kois but rather only to our eyes. To be honest I love the algae grown on the walls and the base of my pond ( I only like the green carpet like algae and not the string and brown colored algae). As for me, I turn on the UV light whenever I sense that there are too much bacteria counts in the filter chambers and in the water especially bringing the pH down to concerned levels. For the swimming uni celullar algae, I let the bacteria colonies in the Biological chamber do the job. I too these days very seldom use the UV as my pond is 99% covered.

    Definitely clear healthy water is desired but not to the extend of being sterile water.
    In Koianswers Forum, no one individual is above the rest. This is the Forum for the Koi Community.
  • lautslauts July 2012
    Posts: 1,163
    Bro HDCu,

    For my pond , i use a 30watt shine on unit for my 60t for only reduction of bacteria bloom. My outdoor is 90% covered from sun but once a while ( every few weeks) i get slight cloudiness which the UV take care off in 2-3 days max. Rather than apply any medication etc , UV is best for this purpose. It then becomes crystal clear. As per Bro Shukri i let the bio chamber do the nitrification.

    ts
  • HDCuHDCu July 2012
    Posts: 1,086
    Bro Lauts,

    Thank you for sharing. You mentioned bacterial bloom as the source of your cloudiness. Ive found some interesting topic why bacterial bloom happens even in an established setup.


    Bacterial Blooms - Explained

    Every fishkeeper has experienced a bacterial bloom at some point. They are common in new set-ups which are cycling, but can happen at any time. The water goes cloudy, almost like someone has poured a drop of milk into the tank, and no matter how many water changes you do, it doesn't go away. Sound familiar?

    I hope to explain here exactly what a bacterial bloom is, the effect it can have, how to treat it and how to prevent it.


    The Nitrogen Cycle

    To fully understand about bacterial blooms, a knowledge of the Nitrogen Cycle is required. If you are unsure of the Nitrogen Cycle or don't know what it is, it may be helpful to read the linked topic below first. This is particularly relevant if you have recently set up the tank, as the cloudiness is most likely an indication of other problems.

    The Nitrogen Cycle


    What is a Bacterial Bloom?

    There are 2 types of bacteria at work in our tanks:-

    Autotrophic Bacteria - Bacteria capable of synthesizing its own food from inorganic substances, using light or chemical energy. Our beneficial filter bacteria are autotrophs.

    Heterotrophic Bacteria - Bacteria that cannot synthesize its own food and is dependent on complex organic substances for nutrition. The heterotrophs in our aquariums mineralise the organic waste (break down the uneaten food, fish waste, dead plant matter etc into ammonia).

    Contrary to popular belief, it is commonly the heterotrophs which are seen in our bacterial blooms, not our trusted autotroph nitrifiers.

    It is the heterotrophs which are primarily responsible for creating the "bio-film" (slimy residue found on the tank walls and ornaments) which builds up in our aquariums.

    The heterotrophs are generally bigger than the autotrophs and therefore don't attach themselves to surfaces with the same ease. They also reproduce much more quickly. Heterotrophs can reproduce in around 15 - 20 minutes, whereas autotrophs can take up to 24 hours to reproduce.

    In a newly set-up aquarium, the heterotrophs get to work quicker than the autotrophs, causing the 'cycling bloom' we so often see. Blooms are almost certainly heterotrophic if they are caused by a build up of organic waste in the substrate, which most, if not all, are.

    Bacterial blooms are common in tanks with apparently no organics present (for example, where all that is in the tank is water and ammonia for a fishless cycle). This is caused by the dechlorination of the water suddenly enabling the water to support bacterial populations. The heterotrophs immediately get to work on the organics in the water itself. The severity of the bloom and even whether a bloom happens at all is dependant upon the level of organics contained in the water supply.

    Our autotroph nitrifiers are strictly aerobic (require oxygen), but the heterotrophs can be facultative anaerobic (they can switch between aerobic and anaerobic function depending on their environment). Therefore the heterotrophs in the substrate will be in their anaerobic state and breaking down the organic waste into ammonia, but if they bloom up into the water column, they will switch to their aerobic form and will start to convert the ammonia back to nitrite, although very inefficiently. The heterotrophs are around 1,000,000 times less efficient at ammonia oxidisation than our beneficial autotrophs as the heterotrophs are not true nitrifiers.


    The Effects of a Bacterial Bloom

    Most of the bacteria in the aquarium are aerobic as it is a oxygen dominated environment, and these bacteria require lots of oxygen. When the heterotrophic bacteria bloom into the water column and switch to their aerobic state, this is a big drain on the oxygen content of the water. Oxygen depravation is the only risk to the fish which i am aware of during a bacterial bloom, as the heterotrophs themselves are harmless to fish, so good advice is to increase aeration!

    To help you to understand why bacterial blooms occur, overfeeding ,dead fish or dead plant matter will cause a rise in the reproduction of the heterotrophs in order to break down the organic waste, they re-produce too quickly to be able to attach themselves to a surface and this causes a bacterial bloom. As the ammonia production increases due to the increased mineralisation, the nitrifiers are slow to catch up (as i said above) and so you see an ammonia spike until the autotrophs reproduce enough to take care of it. Contrary to popular belief, bacterial blooms cause an ammonia spike, not the other way around.

    It is unclear whether the autotrophic nitrifiers ever bloom into the water column or if they simply multiply too slowly to cause this effect.


    Treatment and Prevention of Bacterial Blooms

    A thorough gravel vac will certainly help the situation, as will trying not to overfeed. Also, increase aeration as I noted above. Water changes will probably not clear the cloudiness as when you remove the free-floating heterotrophic bacteria, the others will reproduce more to compensate. Given the reproduction rate of the heterotrophs, it would require a 50% water change every 15 - 20 minutes just to stop the bloom getting worse, and even more if you want to make any progress towards clearing the bloom.

    However, water changes won't exacerbate the situation as it will be heterotrophs (which are producing ammonia) which are removed from the water column via the water change. A water change will remove virtually no nitrifying autotrophic bacteria from the tank at all as 99% of the nitrifiers are housed in the filter, not in the water column. Water changes are not essential in clearing bacterial blooms, as left alone, they will usually dissipate within a matter of days.

    Reducing the amount of organic waste in your tank is the ultimate solution to treating a bacterial bloom, and avoiding a build up of organic waste in the tank is the best way to prevent a bloom. The best way to do this is to maintain a regular aquarium husbandry routine involving water changes and substrate vaccuuming.

    As I said above, blooms are common in tanks with apparently no organic waste present, most commonly when only water and ammonia are in the tank for a fishless cycle. In this case, there are few easy ways to remove the organics from the water, and so my best suggestion is to sit it out and wait. Water changes with purified water would help as it would dilute the concentration of organics in the water. Reverse Osmosis water would be ideal in this situation, however i would suggest that patience is the cheaper and more environmentally friendly option.

    A bloom in an established tank indicates that there is a problem which has allowed a build-up of organic waste, usually in the substrate. This can be caused by excess dead plant matter, over-feeding which leaves food lying around the tank, or leaving dead fish in the tank. None of these are desirable in an aquarium and a bloom in your established tank will certainly indicate one or more of these causes present in the tank. If you experience a bloom in an established tank, improve your husbandry.

    Please note: Unless otherwise stated, all text and images in this post are copyright Backtotropical, 2008-2011.
    This post has been edited by backtotropical: 19 February 2011 - 06:39 PM
    Post edited by HDCu at 2012-07-11 06:47:28 pm
  • vinsonchuavinsonchua July 2012
    Posts: 163
    Great read, thanks. Bro HDCu
  • lautslauts July 2012
    Posts: 1,163
    THANKS (Y) bro HDCu,

    Few things i note:
    a) "Bacterial blooms are common in tanks with apparently no organics present (for example, where all that is in the tank is water and ammonia for a fishless cycle). This is caused by the dechlorination of the water suddenly enabling the water to support bacterial populations." - One reason not to dechlor ? :O

    b) "When the heterotrophic bacteria bloom into the water column and switch to their aerobic state, this is a big drain on the oxygen content of the water. Oxygen depravation is the only risk to the fish which i am aware of during a bacterial bloom, as the heterotrophs themselves are harmless to fish, so good advice is to increase aeration! "
    - One major reason why kois dies in QT , lack on o2.

    c) "Water changes are not essential in clearing bacterial blooms, as left alone, they will usually dissipate within a matter of days. - is UV helping to cut down bloom days ? or it naturally subsides ?

    ts
  • ShukriShukri July 2012
    Posts: 4,870
    Good job there bro Lauts & HDCu, good reading for all of us........... (Y)
    In Koianswers Forum, no one individual is above the rest. This is the Forum for the Koi Community.
  • MikeMike July 2012
    Posts: 345
    Good info HDCu. Thanks.

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