about UV lights
- Thread starter GarNiac
- Start date
Yup. That what they do. Also kill water living algae ie. green water.....GarNiac;4736429;4736429 said:
I think a lot has to do with the amount of time the water is exposed to the UV light. For the most effective treatment you want long exposure, thus the reason many are designed with a water flow that goes around the bulb multiple times like the turbotwist.
UV-C is effective up to a certain distance from the bulb. I don't remember what it is offhand but the diameter of UV sterilizer housings is based on that value. Let's say it's 2", resulting in housings with diameters of 4". Stick some spiral fins in there (which are likely not UV-C-transparent) and water at any point along the spiral is shaded from the bulb on two sides.
Now consider an older design that had a spiral tube of water wind around the bulb. With the effective zone being a 4" cylinder around the bulb, that design filled a lot of that area with air instead of water. Irradiating air does no good.
This is why none of the expensive brands (AquaUV and Emperor Aquatics) have spiral gimmicks. If the flow needs to be reduced, it's best to accomplish it via another method.
Secondly, there's always a lot of talk about how slow flow is necessary but it is not the only thing to consider. Imagine a pond with a few thousand gallons of water. Could a 5W sterilizer be made to work simply by slowing down the flow sufficiently? No, because the overall flow through the sterilizer is too low. The algae or whatever you're trying to eliminate will reproduce faster than it can be eliminated outside the sterilizer.
Now imagine an aquarium with a properly sized UV sterilizer. Whatever organism you want to kill requires 3 seconds of exposure but you slow down the flow so it has a 6 second exposure but a turnover rate of 5X per hour. It's probably more efficient to got with 3 seconds and 10X. However, there are so many variables that it would be hard to determine the most efficient turnover rate.
Now consider the fact that UV damage is cumulative. What if you increased the flow rate to 30X and exposure to 1 sec? Well, one benefit "micro-dosing" UV is that you avoid the problem of over-sterilizing (overdosing with UV) the water in the sterilizer and giving organisms in the tank more time to repair and reproduce.
The point is that exposure time is not the be-all, end-all of sterilization as it is in single-pass drinking water systems where you have one and only one shot to sterilize the water before it's consumed.
Now consider an older design that had a spiral tube of water wind around the bulb. With the effective zone being a 4" cylinder around the bulb, that design filled a lot of that area with air instead of water. Irradiating air does no good.
This is why none of the expensive brands (AquaUV and Emperor Aquatics) have spiral gimmicks. If the flow needs to be reduced, it's best to accomplish it via another method.
Secondly, there's always a lot of talk about how slow flow is necessary but it is not the only thing to consider. Imagine a pond with a few thousand gallons of water. Could a 5W sterilizer be made to work simply by slowing down the flow sufficiently? No, because the overall flow through the sterilizer is too low. The algae or whatever you're trying to eliminate will reproduce faster than it can be eliminated outside the sterilizer.
Now imagine an aquarium with a properly sized UV sterilizer. Whatever organism you want to kill requires 3 seconds of exposure but you slow down the flow so it has a 6 second exposure but a turnover rate of 5X per hour. It's probably more efficient to got with 3 seconds and 10X. However, there are so many variables that it would be hard to determine the most efficient turnover rate.
Now consider the fact that UV damage is cumulative. What if you increased the flow rate to 30X and exposure to 1 sec? Well, one benefit "micro-dosing" UV is that you avoid the problem of over-sterilizing (overdosing with UV) the water in the sterilizer and giving organisms in the tank more time to repair and reproduce.
The point is that exposure time is not the be-all, end-all of sterilization as it is in single-pass drinking water systems where you have one and only one shot to sterilize the water before it's consumed.
I use my 2-5 watt UV lights in my hang on filter(75 gallon tank), I use this method instead of a larger bulb, takes alittle more time to cure the problem, but gives time for the beneficial bacteria to keep growing and keeps my fish nice and healthy. I usually use my uv lights for green water(free flowing algae). Takes longer for the green water to clear up but does clear up my water. I have never used a high watt uv light. I dont know what you need those lights for, but also helps if you have a bacteria outbreak(cloudy water), in your tank. I put alot of care into my tank. Hope this helps.