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#16
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UV steralizer
I agree with liz regarding incandescent bulb life being shortened by
power cycling, though I always attributed it to the temperature cycling (effectively causing the metal filament to fatigue). Cycling fluorescent bulbs is also supposed to reduce their life expectancy, but I don't know the mechanism. The ballasts will also be a consideration. I'd contact the manufacturer to see what they recommend for maximum life. One of the fluorescent manufacturers (Phillips, GE etc) might have data on their websites as well. note to Donald, ..turnover/..html... book-marked ) NetMax "liz bolyard-mick" wrote in message ... I may be wrong, but I believe that only incandescent bulb life is shortened by turning it off and on due to the surge of electricity passing through the filament. This surge weakens the filament by vaporizing pieces of the filament. During normal usage, samll pieces of the filament detatch and float freely in the bulb, but they are drawn back to the filament to settle on it. It is the vaporization of the small pieces of the filament that shortens the life of an incandescent bulb. I don't believe the same is true for any flourescing type lamp, but I don't know as much about those types. "Bruce Geist" wrote in message ... Basically, you are only culling the population of algae spores and bacteria to a level, presumably, that is more like an open stream or lake. All tank water is never sterile at any one moment in time, since algae and bacteria are constantly re-growing. To control a specific organism or class of organisms, use the lowest lethal dose for that organism or class of organism, meaning you turn your flow rate up so that water passing though is exposed to the right level of radiation, and no more. That way, you are killing algae at the quickest possible rate. The flow rate is effectively your control on the dosage you are delivering. So, if algae is your target, I'd turn your flow rate to about 200 gallons per hour. This will deliver (I am estimating here) about 50,000 micro watt-seconds / cm^2 of radiation to the water passing through your sterilizer. Here is the shaky part; I am not sure exactly what dose will kill all algae. So be aware, I am making a swag here. I do know that Chlorella Vulgaris, a kind of algae, is killed by 45,000 micro watt-seconds / cm^2 of UV. Therefore, I am recommending a flow rate that I believe will cause your 36 watt sterilizer to deliver the 50 K micro watt-seconds / cm^2 dosage. I do not actually have intensity data for your particular sterilizer, though I have requested it from the manufacturer (because I am doing some mathematical modeling for an article I am writing..) I have intensity data for a 30 and 64 watt UV set-up, so I am interpolating a result here. However, the dosage estimate is really an estimate! Sorry I cannot be more precise. Now its your choice whether to leave on the sterilizer or cycle it. I do not believe the statement that cycling a UV lamp shortens its life significantly. Maybe it does, but I find it hard to believe. In fact, the lamp manufacturer defines its useful life in terms of hours on, not number of cycles. If you leave the thing on all the time, the lamp will last about 6 months. If you use it only during the day, my expectation is that it will last a year. Since your target is algae, maybe its enough to sterilize when the algae is multiplying during your tank's lighted period. Do some experiments, and see if you perceive a difference in water quality and/or algae proliferation when cycling and not cycling. And then let me know what you conclude! I'd really like to know what your experience turns out to be... -Bruce http://www.wideopenwest.com/~brucegeist "Christopher" wrote in message rthlink.net... Thats a very detailed explanation, THANKS! have a couple questions though: if the primary reason I'm using the steralizer is to kill algae spores so my tank stays clean is it smart to only have the steralizer running for X hours a day? Cant the spores be released and land and settle on the glass and leaves during the off period? My second question is how much life of the bulb is saved when you run it for 8 hours a day? I know that the turning on of the bulb takes away from bulb life, but would the fact that its only run for 1/3 of the time save bulb life in the long term? I am concerned since 36W PC florescents are $50 (not exactly cheap) "Bruce Geist" wrote in message ... Actually, the 9.2 factor will give you 99.99 % throughput through the sterilizer. To get 99.9% throughput, the factor is 6.9. See http://www.wideopenwest.com/~brucege...ver/index.html for details. One strategy is to set the flow rate through the sterilizer so that one pass kills target organisms you wish to kill. If you set the flow rate slow enough that everything you want to kill is killed, then run your sterilizer long enough to "turnover" the tank water once or twice a day, and then shut the sterilizer off. Basically, the more slowly you put water through the sterilizer, the more UV exposure every bit of water passing through the sterilizer receives. If you have a 36 watt sterilizer with about a 3 inch diameter chamber for the water, and your flow rate is about 100 gallons per hour, then you are probably irradiating your water at about a 100 microwatt-seconds dose, which is enough to kill most bacteria, algae, and many protozoa. (This is only a crude estimate; I am working on developing some assessment tools on my website which will provide more specific advice..) If you are using a lower wattage sterilizer, or a lower diameter sterilizer, then your flow rate will need to be lower still to achieve the same dose. In the article I wrote cited above, I show that when you have run 99.9% of the water through the sterilizer at least one time, in actuality 99.2% of water has passed through 2 or more times, and 96.8% will have passed through the sterilizer 3 or more times! I recommend 6.9*(tank size in gallons)/(flow rate in gallons) to be your target turnover time. If your flow rate is chosen with some care, you need not run your sterilizer all the time. You will save bulb life by running your sterilizer through only one or two turn-over intervals per day. I hope you enjoy the article on turnover time; this is the first time I have published the web address. Remember that you can skip to the conclusion and get the formula to use. I am in process of collecting data for a suite of articles on the topic UV sterilizers. Be watching this news group or my web site; I am waiting on data from a manufacturer. -Bruce Geist "Christopher" wrote in message rthlink.net... is it wise to run the UV steralizer 24 hours a day? assuming that you only desire a 99.9% steralization rate you don't have to run the steralizer that much (depending upon gph through the steralizer and tank size). I've read: 9.2 * (tank size / gph through steralizer) = hours a day UV steralizer must be on to attain 99.9% steralization rate (assuming uniform mixing). This said my calculation is at most 7 hours a day, should I just run it for 8 hours a day and save my bulb life and power bill? Should I run it 24 hours a day to achieve 99.999% steralization or for 8 hours a day? |
#17
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UV steralizer
I know for most people it isn't a big deal but I don't like algae
in my tank and for me... It's not just you. Most people hate algae in the tank. That way I can run the lights more than 8 hours a day and I don't have to spend an hour scraping the sides of the tank every other week. Most people don't have UV sterilizers and don't have to spend an hour scraping the tank, either. If your tank is in balance, your algae problems should be minimal. And you should have your lights on more than eight hours a day. Aquarium plants generally need a 12 hour day. You should not go below 10 hours. Too short a photo period can actually help algae, since the plants won't be growing as well as they should. Leigh http://www.fortunecity.com/lavender/halloween/881/ |
#18
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UV steralizer
well I'm up to 12 hours of full light and 30 minutes of sunrise and 30
minutes of sunset full light is 120W (80W power-glo 40W actinic 03) sunrise/sunset is 40W actinic 03 all over a 125g "LeighMo" wrote in message ... I know for most people it isn't a big deal but I don't like algae in my tank and for me... It's not just you. Most people hate algae in the tank. That way I can run the lights more than 8 hours a day and I don't have to spend an hour scraping the sides of the tank every other week. Most people don't have UV sterilizers and don't have to spend an hour scraping the tank, either. If your tank is in balance, your algae problems should be minimal. And you should have your lights on more than eight hours a day. Aquarium plants generally need a 12 hour day. You should not go below 10 hours. Too short a photo period can actually help algae, since the plants won't be growing as well as they should. Leigh http://www.fortunecity.com/lavender/halloween/881/ |
#19
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UV steralizer
"Christopher"
UV's have a couple of planted tank uses. One is for green water The other is for the 24 hour period after a water change. So you will only need to use it once a week after the 50% water change. They do no good after this period. I don't use them on my tanks personally. Don't need too. Try a credit card for getting algae off the glass. I think you'll find this is the best use for a credit card rather than it's intended purpose. If you address the CO2/nutrients, cleaning the glass is seldom an issue. Regards, Tom Barr |
#20
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UV steralizer
The other is for the 24 hour period after a water change.
Why for a 24 hour period after a water change? (Just curious -- I've never heard that one before.) I originally got my UV sterilizer to prevent ich. I just couldn't face prophylactic treatment with chemicals for a 75 gallon tank, over the long weeks of stocking using Chuck's "no-cycle" setup. I've left it on since, mainly to knock bacteria levels down closer to the natural levels you find in lakes and streams, but I'm thinking of turning it off. It's one more powerhead to clean, and I'm lazy! Leigh http://www.fortunecity.com/lavender/halloween/881/ |
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