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  1. #21
    Just an Egg
    Join Date
    Mar 2008
    Los Angeles, CA
    Anyone have any advice on how often to switch out UV bulbs? Most sources I've read say 6 months with a smattering of anywhere from 3 months up to 1 year suggestions. Any thoughts?

    I'm running one of these btw:

  2. #22
    Join Date
    Nov 2008
    Hunter Valley NSW
    I have been told by a couple of peopl they can last past a year but replace every 12 months, but I guess cheaper ones wouldn't last as long as the dearer ones.

    I am using a Laguna UV. See link

  3. #23
    Medium Discus
    Join Date
    Sep 2007
    East of Melbourne


    I am hoping that between those here with some experience using UV filters that you may be able to answer my question. What UV filters are easily cleanable ? I ask this as I have used some that will not come apart (other than to change the bulb) so I cannot clean the tube thereby ensuring the light intensity / exposure remains constant.


  4. #24
    Join Date
    Jan 2007
    Penrith NSW
    What are peoples opinions on the new generation of UV sterilizers? The ones that use germicidal ozone generating grade lamps? Aqua ultraviolet, pentair, emporer are brands that come to mind.

    The tech data on these units is better then it has ever been clearly stating on each unit the output in uw(s)/cm2 (microwatt seconds/ square centimeter) at various flowrates (some even end of life ratings on the bulbs).

    Still I'm a little dissapointed that most seem to maxout at ~90000. My understanding is that larger protozoa will tollerate irradiation at up to 200000.

    I'm aware that the benchmark is whitespot with has 99.99% kill rate at 45000, but what is the opinion of people here as to a reasonable output for UV to be concidered effective?

  5. #25
    Hi, I'm New Here!
    Join Date
    Jun 2010

    Hey guys some info on uv lighting

    I read this and thought it may be of some use.

    The first you have to remember is that not all organisms are killed by the same amount of UV; it all depends on the dose rate of UV passing through the water.

    To start with, here are the things we need to know to effectively size a UV sterilizer -

    1. The organism (or range of organisms) you want to kill or prevent from getting a foothold in your tank.

    2. The size of the body of water/tank you have

    3. The flow you have in that tank

    For example if you had a 4000 liter pond, and a flow rate in that pond of 4000LPH (or more it doesn’t really matter), you would only need to size the UV sterilizer to and Algae and Bacterial flow rate of 30,000 Microwatts and only pass the volume of the pond through the UV over a 4-6 hour period, meaning that you would need a flow rate of between 700 - 1000LPH on a by-pass to the main flow of water.

    This would result in around an 18 watt UV sterilizer sized at 30,000 microwatts.

    As Algae generally reproduces every 4-6 hours, passing the entire volume of the pond through the UV faster then this will eventually stop the life cycle of the algae and prevent it from growing. Obviously passing more water through a larger UV will get the job done quicker.

    The second application is sizing the UV to the aquarium size, generally this size should be calculated by taking the recommended flow of the UV sterilizer at algae and bacterial flow rates and dividing the flow by three (three times per hour turnover rate). Then if you have a higher turnover rate but do not want to size the UV to the flow rate you can just stick to the recommend flow rate and Aquarium size.

    Then as a different application say you had a very large tank, Retail tank system, quarantine system etc and you wanted a higher rate of sterilization. You would first find the flow rate of your system, say this was 6000 liters per hour; there are two ways to know size your UV sterilizer in this application.

    The first is Bacterial and Algae treatment (at 30,000 microwatts) and will generally kill most types of bacteria and algae. You would pass all of the water through the UV and therefore at a bacterial and algal treatment rate for a flow rate of 6000 LPH the system would require a 50 watt UV sterilizer. By passing all the water through the UV sterilizer from the pump you make sure that all the water going back to tank has been treated by the UV.

    Now in most cases I would recommend sizing a UV to the protozoal treatment rate (90,000 microwatts - 3 times bigger) for these sorts of applications.

    So if it were the same application as above you would be looking to size a UV between a 120 watt and 150 watt UV.

    Now you must keep in mind that not all UV sterilizers are created equal. For instance the Emperor Aquatics UV sterilizers are based on a standard 30,000 microwatt bulb and the flow rates are based on 80% transmissibility through the water (green water/algae and particulate laden water) and a 60% bulb life which is end of bulb life, so when you size a UV you know that you will get that level of sterilization out of the UV even when the bulb is close to the end of its life after 9000 hours continuous operation.

    However some bulbs, in fact a vast majority of them are only sized on a 15,000 microwatt bulb, making comparing UV models harder. For instance an 8 watt UV with a 15,000 microwatt bulb is only half as effective an 8 watt UV with a 30,000 microwatt bulb because the dose rate of UV through the water is only half that in 15,000 MW UV.

    So in conclusion the effectiveness of a UV depends on:
    - The wattage
    - The dose rate of UV light in Micro-watts per second per square centimeter (uWS/cm2)
    - The flow rate or contact time inside the UV chamber in relation to the two above factors

    Several other factors effect the value and effectiveness of the UV such as the way the bulbs are sized (end of bulb life or new bulb), the transmissibility through the water (sized on particulate laden - 80% transmissibility or clear water) and the overall design of the UV itself for instance emperor UV units have the bulb positioned between the inlet and outlet and not beyond these points, so that the water passing through the unit is exposed to the entire length of the UV bulb.

    For disease control if you can afford it, go with at least a UV sized to 30,000 MW that will handle the entire flow rate from your return pump. for even better disease control upgrade to a UV that will handle all the flow from your return pump that has an output dose rate of 90,000 MW.

    Below is a table that details some different organisms and the relative dose rate of UV needed to kill them/inactivate them.

    Microorganism UV Dosage (µW sec/cm2)
    Aeromonas salmonicida 3,620
    Bacillus subtilus (vegatative) 11,000
    Bacillus subtilus spores 22,000
    Bacillus megaterium (vegatative) 2,500
    Bacillus megaterium spores 52,000
    Bacillus anthracis 8,700
    Bacillus paratyphi 6,100
    Campylobacter jejuni 4,600
    Clostridium tetani 22,000
    Corynebacterium diptheriae 6,500
    Eberthella typhosa 4,100
    Enyerococcus faecalis 10,000
    Escherichia coli 6,600
    Lactococcus lactis 8,800
    Legionella bozemanii 3,500
    Legionella dumoffi 5,500
    Legionella pneumophila (Legionnaires' disease) 3,800
    Legionella gormanii 4,900
    Legionella longbeachae 2,900
    Legionella micdadai 3,100
    Leptospira interrogans 6,000
    Mycobacterium tuberculosis 10,000
    Neisseria catarrhalis 8,500
    Proteus vulgaris 6,600
    Pseudomonas aeruginosa 3,900
    Rhodospirillum rubrum 6,200
    Salmonella 10,000
    Salmonella enteritidis 7,600
    Salmonella paratyphi (enteric fever) 6,100
    Salmonella typhimurium 15,200
    Salmonella typhosa (typhoid fever) 7,000
    Serratia marcescens 6,200
    Shigelia dysenteriae 4,200
    Shigelia flexneri 3,400
    Shigelia sonnei 7,000
    Staphylococcus opidermidis 5,800
    Staphylococcus aureus 7,000
    Staphylococcus hemolyticus 5,500
    Staphylococcus lactis 8,800
    Staphylococcus viridans 3,800
    Vibrio cholerae 6,500

    Chlorella vulgaris 22,000

    Channel Catfish Virus (CCV) 20,000
    Chum Salmon Virus (CSV) 100,000
    Infectious Hematopoietic Necrosis Virus (CHAB) 20,000
    Infectious Hematopoietic Necrosis Virus (RTTO) 30,000
    Infectious Pancreatic Necrosis Virus (Buhl) 150,000
    Oncorhynchus masou virus 20,000
    Bacterilophage 6,600
    Hepatitis 6,600
    Influenza 6,600
    Poliovirus 21,000
    Rotavirus 24,000
    Tobacco mosaic virus 440,000

    Saprolegnia hyphae 10,000
    Saprolegnia zoospores 39,600

    Mold Spores:
    Aspergillus flavus 99,000
    Aspergillus glaucus 88,000
    Aspergillus niger 330,000
    Mucor sp. 35,200
    Penicillium sp. 88,000
    Penicillium expensum 22,000
    Penicillium roqueforti 26,400
    Rhizopus sp. 220,000

    Phytomonas tumefaciens 8,500
    Paramecium 220,000
    Icthyophthirius sp. (tomite) 336,000
    Cryptocaryon irritans (white spot disease) 300,000
    Cryptosporidium parvum 7,900
    Sarcine lutea 26,400
    Ceratomyxa shasta 30,000
    Costia necatrix 318,000
    Myxosoma cerebralis 35,000
    Trichodina sp. 35,000
    Trichodina nigra 159,000

    "In order to form an immaculate member of a fish tank one must, above all, be a discus."

  6. #26
    Hi, I'm New Here!
    Join Date
    Apr 2011
    The system can be used with ultraviolet radiation in combination with activated carbon filters or RO to remove the minerals and particles which may shield microorganisms from UV radiation.

  7. #27
    Join Date
    Sep 2006

    Great info

    Thanks for that pb, helps a lot

  8. #28
    Join Date
    Jan 2007
    Penrith NSW
    Awesome info!!!

    as i keep telling people here aim for 90000uW as a minimum its what you need to keep on top of infections that get to discus.

    also remember that your discus tank has transmission rates >95% (super clean clear water) so you can usually get away a slightly smaller UV then those calculated at 80% transmission (ie green water as found in ponds).

  9. #29
    Hi, I'm New Here!
    Join Date
    Aug 2004
    North Ryde, Sydney NSW
    It's been a long time since I've posted here, but 'domestic' Ultra Violet Clarifiers have come a long way in nearly seven years, and prices have dropped dramatically!

    The latest models are stainless steel, because this provides up to 35% more UV efficiency from the electrolytically polished reflective stainless steel barrel interior over non-reflective black plastic UVC models.

    The Jebao STU-75W UVC is the first such model available.

  10. #30
    Eternal Moderator Merrilyn's Avatar
    Join Date
    Jul 2004
    Melbourne Vic.
    Good to have you posting again DeKa.

    I'm in the market for a top of the line UV for a 300 litre tank. What would you recommend?
    Thirty-five years keeping and breeding discus, and I'm still learning :P

    Merrilyn has passed, but will not be forgotten - Goodbye dear friend

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