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Discussion Starter · #1 ·
Hi Folks,

I did a bit of rescaping yesterday, kicked up a lot of stuff, scraped a lot of algae and thought I'd break out the UV to kill algae and anything suspended.

the UV is a gamma HOB, 24 watt sterilizer. Lots of horsepower. Tank is 84g, pump is a mini-jet 606 @160gph.

Question is, how long is enough to thoroughly polish a 85 tank at this flow rate? Ran it overnight so I think I'm done, but for the future what do you think - 3hrs, 4hrs, 3 days....?

What do you think?
 

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UV should not run all the time in a planted tank. And putting it on a timer is the same thing as running it all the time.

If you are using UV to clean up the water because of a rescape, or uprooting plants, or something like that, you will only need to keep it on until the water goes crystal clear, at which time you would remove it again.

If your water just wants to keep clouding up all the time, you've got problems, and you need to figure out what's causing the cloudiness to occur... not just cover it up by using UV.
 

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Well then sure it happens. And that is when it is appropriate to turn on the UV. But once the water is spotless again, I turn it off. There is a lot of evidence that suggests UV breaks down micronutrients over time. Obviously this is bad on a planted tank that is dosed with micronutrients.

I'm simply saying, the name of the thread is "How long to run UV," and the answer is "Until the water is clear."
 

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Discussion Starter · #12 ·
Thanks Church.... The filter cleans up any cloudiness very quickly. I just use it for an occassional polishing. I'd been thinking that wiping out water-born pests once in a while was a good thing. Finally bought it to help with an Ick attack. Now I use it if I do anything that stirs up a lot of muck as that seems like a good time to kill off anything lingering. I plan to use it just as an extra precautuion after introducing new fauna and for an occassional polishing.

I guess the real question regarding duration is how long a 160gph pump should take to turn the water over thoroughly a few times. Assuming water looks clear before the last nasty is dead....so was just wondering how much "extra" time would be optimal.

Thanks as always. It is funny that even though I think the water is very clear, it downright sparkles after a few hours of UV.

AB
 

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OK, the engineering answer is - it depends.
I'm not an engineer, but I did read Stickney's "Principles of Aquaculture".

The appropriate answer does happen to be - it depends - on the size of the tubing, pump capacity, the diameter of the filter, wattage and length of the bulb, and what you want to kill. Water has to run long enough past the correct wattage bulb for the UV to sanitize the water. Too fast and little to no sanitizing occurs. Too slow and you waste bulb life.

On the good side, UV bulbs are relatively inexpensive if purchased from http://uvdepot.com/
With which I have no association, discounts or freebies.
 

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Discussion Starter · #14 ·
Thanks dbosman. You're right. I bought the 24w T5 fixture because it is rated to kill protozoa at up to 400gph flow, algae at 1200 (hehe 1200). Even 400gph requires less convenient plumbing than a smaller pump so I went with the mini-jet, which fits perfectly, makes a single unit and is very convenient to Hang-on, Take-off the fixture.

On sale at Dr. Smith and Foster (Can I say that?) the Gamma was a good long-term buy. Probably overkill for 85g, but who knows what is next, so...

Thanks for the input.
 
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