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How long does a UV clarifier take?



 
 
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  #1  
Old 05-04-2008, 04:55 PM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default How long does a UV clarifier take?

Hi

I only have a 1064L pond (about 1.4m x 1.9m x 0.4m), and have been trying for a year and half to make it clear naturally. So have pond plants and a normal bio filter (one of them boxes with foam and sections of pipes in it). But have failed to clear it naturally so installed a Tetra 9W 8000L UV clarifier. Its installed just before the water goes into the filter.

The guy at the garden centre said it should take 4 to 5 days and it will end up crystal clear. But its been on about a week now and I cant see any difference, pond is still pea soup. I can only see an inch or two down.

The filter light is on indicating it working (although I assume UV light is invisible so I cant tell if the bulbs are working but the bulbs dont look broken). I dont know what pump is being used.

I wondered how long these things usually take to work? And if it clearly is not working what could cause it to not work considering the UV clarifier is working and the bulbs dont look broken.

Thanks!
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  #2  
Old 06-04-2008, 12:14 AM posted to rec.ponds.moderated
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Posts: 93
Default How long does a UV clarifier take?

That's interesting... My Aquaultraviolet UV said to install it just
*after* the filter, on the return...

The thing about UV is that the bulbs really need to be replaced every
year because they become ineffective, and it's really important to get
the right amount of UV for your pond size. I always oversize these
things. It's also important to have the flow high enough so that the
water is getting changed over at the correct rate too. I'm not sure of
the requirements or size limitations for the Tetra UV. 9 watts seems
really small, but maybe that's because I'm used to a larger pond.

The first thing I'd verify is that you really want to put the UV
*before* your filter. Doesn't UV kill the good bacteria? Then check
the flow requirements for the UV and the pond size limitations.

Oh, and for mine, it takes only a few days to notice a big difference.

- Dave


  #3  
Old 06-04-2008, 07:21 AM posted to rec.ponds.moderated
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Posts: 93
Default How long does a UV clarifier take?

Hi, I have a little more info on this.

I checked the manual for my UV, and it says that the best place to
install it is after the filter.

"If an after filter installation is not feasible, your sterilizer can
be installed before the filter, but it will take a little longer to
work."

The unit I have can be used to clarify or sterilize, so that's why
it's referring to the unit as a sterilizer. It goes on to say that if
you do a pre-filter installation, you should be aware that even a
small stone can pass into the unit and cause breakage. Good point.

Also,

"Ultraviolet light does not discriminate about what it destroys. If
good bacteria passes by the light it will be destroyed."

So, the takeaways a It takes longer for a clarifier to work if it's
before your filter, there's more risk of breakage if it's before your
filter and it will kill good bacteria if it passes through. Normally
the bacteria won't be free floating like that, but if you're seeding
your pond and your filter with bacteria, you'll want to keep the UV
off until they've colonized in your filter and on the pond walls.

Maybe it's just your placement of the UV that's making things take
longer. If you really have pea-soup water, you'll need to be actively
cleaning your filter, since it should be filling up with the dead
stuff. I'm not sure what kind of filter you have capacity-wise, etc.
but that may be a consideration as well.

My first pond was installed by a landscaper who didn't specialize in
ponds. I was naive enough to believe it when he said he was an expert
on pond construction. I quickly learned more than that landscaper
after I ran into problems like green water. In the case of that pond,
the pump was undersized for the pond size, the "filter" was one of
those small pass-through filters that sits on the bottom of the pond,
and the pond was put smack under several healthy pine, sycamore, and
maple trees, which made for a memorable Fall clean-up.

The next summer, I ended up enlarging the pond (just cuz), adding a
skimmer, adding a bead filter, adding UV and tossing the pond-bottom
filter. I suppose those work for very small ponds, but I wasn't
impressed with the one I had and they're a pain to clean. That pond
was about 3,500 gallons and the filter was useless for that. Without
mentioning any names, it's the same kind of "pond filter" you can find
in your local pet store.

That pond was still a pain because of the trees, but the skimmer was a
godsend and the UV, larger pump and better filter kept the water
clear. The combination of flow, filtration and UV (if you opt for it)
is important, because the whole system needs to be matched. A wimpy
pump on a beasty filter or correctly-sized UV will not do much good.
So, try to make sure that all the pieces are spec'd for each other. I
mentioned before that I tend to oversize all these things and that's
because I've found that it doesn't take long before you have more fish
in the pond than you ever intended. Fish aren't big on abstinence.
Over-sizing the filtration and such gives you a little more time to
deal with that inevitable problem.

Anyway, I hope the extra UV info might be of some use. This is the
tough time of year algae-wise, so hang in there.

Best,

Dave

  #4  
Old 06-04-2008, 10:23 AM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default

Thanks for your replies.

Clarifier after the filter... thats interesting. I checked the manual and doesn't even say where to put it! I thought I heard the guy at the garden centre say where to put it, but I could be mistaken. I remember now, I think he said "the UV filter will kill the algae then the bacteria in the filter will clean up the dead algae" or something like that so I assumed UV first, filter second.

I'll have to call them up and ask them.

The manual does recommend a Tetra pump to use with this filter, perhaps my pump is too fast or something (I read in another post someone saying the flow could be too fast for the clarifier).
  #5  
Old 06-04-2008, 10:38 AM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default

Oh i remember the garden centre guy saying the clarifier can be fitted to the top of the filter which is what I have donw. I was going to move the clarifier after the filter but realised from the filter to the pond is gravity fed, and the pond to filter is pump fed. If I moved the clarifier it would have to be below the filter and be gravity fed and I dont have room for that so will leave it where it is and see if it works.
  #6  
Old 06-04-2008, 10:46 AM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default

another question though... is UV light invisible? I just found one website saying you can monitor the light through the inlet/outlet. I thought it was invisible. If you can see it them my clarifier is not emitting any visible light.
  #7  
Old 06-04-2008, 04:09 PM posted to rec.ponds.moderated
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Posts: 1,004
Default How long does a UV clarifier take?

Pea soup algae grow because there is excess ammonia or nitrates in the pond.
The filter needs to remove the algae faster than the remaining algae can reproduced
due to the excess wastes.
OR, reduce the waste load. How many fish in this 280 gallon pond?
UV doesnt kill the algae, it clumps them so they are less likely to slip thru the
filter. If your filter isnt removing the clumped algae, then they putting the
nutrients right back into the pond. If you put polyester batting into your filter
you will remove that algae, but then you need to take the batting out when it is
loaded and either clean it (squeeze into clean water) or toss it and add more
batting.
A UV filter does work better after the filter if there are a lot of "solids" in the
water. Other "stuff" protects the algae from the UV.
Often the glass in the chamber that holds the UV bulb becomes clogged with algae,
etc. so it is necessary to clean the "window" or the bulb itself. UV lights can
last years as long as other measures are taken to keep waste levels low. Like a
veggie filter.
Ingrid


On Sat, 5 Apr 2008 16:24:00 EDT, lawr_1 wrote:
I only have a 1064L pond (about 1.4m x 1.9m x 0.4m), and have been
trying for a year and half to make it clear naturally. So have pond
plants and a normal bio filter (one of them boxes with foam and
sections of pipes in it). But have failed to clear it naturally so
installed a Tetra 9W 8000L UV clarifier. Its installed just before the
water goes into the filter.


  #8  
Old 06-04-2008, 04:10 PM posted to rec.ponds.moderated
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Posts: 1,004
Default How long does a UV clarifier take?

They dont become ineffective in a year.
The slower the flow the more likely that the algae will be exposed the correct amount
of UV to cause clumping.
the good bacteria are not in the water, they form colonies ON the biofilter material.
Ingrid

On Sat, 5 Apr 2008 19:14:56 EDT, Pond Addict wrote:
The thing about UV is that the bulbs really need to be replaced every
year because they become ineffective,

It's also important to have the flow high enough so that the
water is getting changed over at the correct rate too. I'm not sure of
the requirements or size limitations for the Tetra UV.
The first thing I'd verify is that you really want to put the UV
*before* your filter.

Doesn't UV kill the good bacteria?

  #9  
Old 06-04-2008, 04:10 PM posted to rec.ponds.moderated
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Posts: 1,004
Default How long does a UV clarifier take?

It is unlikely that anybody is going to shell out the money for an actual water
sterilizer for the pond. Nor is it necessary.
My UV has its own itty bitty pump, a maxi 1000
http://weloveteaching.com/puregold/care/hardware.html
this clears algae out of a 1600 gallon pond. I have a big pump for my veggie filter,
altho that too may be oversized but it gives a nice waterfall on the other end.
Ingrid

On Sun, 6 Apr 2008 02:21:13 EDT, Pond Addict wrote:
The unit I have can be used to clarify or sterilize, so that's why
it's referring to the unit as a sterilizer.


  #10  
Old 06-04-2008, 06:23 PM posted to rec.ponds.moderated
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Posts: 366
Default How long does a UV clarifier take?

On Sat, 5 Apr 2008 16:24:00 EDT, lawr_1
wrote:

I only have a 1064L pond (about 1.4m x 1.9m x 0.4m), and have been
trying for a year and half to make it clear naturally. So have pond
plants and a normal bio filter (one of them boxes with foam and
sections of pipes in it). But have failed to clear it naturally so
installed a Tetra 9W 8000L UV clarifier. Its installed just before the
water goes into the filter.

The guy at the garden centre said it should take 4 to 5 days and it
will end up crystal clear. But its been on about a week now and I cant
see any difference, pond is still pea soup. I can only see an inch or
two down.

The filter light is on indicating it working (although I assume UV
light is invisible so I cant tell if the bulbs are working but the
bulbs dont look broken). I dont know what pump is being used.

I wondered how long these things usually take to work? And if it
clearly is not working what could cause it to not work considering the
UV clarifier is working and the bulbs dont look broken.


If you don't know how much water the pump is flowing through the UV,
you might have missed an important requirement of UV clarifiers. The
water flowing through the filter has to be in contact with enough UV
to work. If the water flows too fast it doesn't have enough UV light
contact. I doubt the flow is too slow, that would cause the UV to
kill algae and more types of bacteria too. This chart indicates the
max flow of your pump would be 900gph. Your 1064L pond is about the
size of my hot tub pond and I'm running a 1200gph pump on it, so I
would have to reduce the flow or get a larger UV clarifier for my set
up.
http://tinyurl.com/4ycxql

You might have better luck at seeing the blue light coming from a UV
clarifier/sterilizer at night. (My bulb is rated for 11 months use
and comes with a caution that it is harmful to eyes and skin, so I
wouldn't spend a lot of time looking for it in the daylight.)
--
Hal Middle Georgia, Zone 8
http://tinyurl.com/2fxzcb

  #11  
Old 06-04-2008, 06:24 PM posted to rec.ponds.moderated
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Posts: 93
Default How long does a UV clarifier take?

I've noticed a dramatic difference with bulbs that are old vs. new,
and the material I've read does say that the bulbs become ineffective
after about 14 months of use (so maybe every two years). Yes, they
still light up, but they're not doing what they're supposed to be
doing. My experience backs that up. I expect that the bulbs don't just
suddenly become ineffective one day, but rather it's a gradual decline
over time. Replacing them earlier may not strictly be necessary but it
can improve performance.

My UV sterilizer has wipers on it, and the chambers are most
definitely not filling up with algae. Rather, the bulbs themselves
become less effective over time. However, in a situation where the UV
is before the filter, I think you could have a major "gunk up" problem
that would make the unit ineffective.

The "sterilizer" vs "clarifier" difference is only based on the size
of the unit compared to the size of your pond. I agree you don't need
a unit acting as a sterilizer, but a sterilizer is just the same
"clarifier" unit, handling a smaller water capacity. At least that's
how the Aqua Ultraviolet units are.

You're right, the UV doesn't kill the algae, it sterilizes the free-
floating stuff. It kills smaller things that pass through it such as
bacteria, viruses, fungi and so on.

I'm surprised to hear that you need UV with a vegie filter. Isn't the
veggie filter alone enough to control the algae or do you use the UV
for other reasons?

- Dave

  #12  
Old 06-04-2008, 10:08 PM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default

I'll have to see if I can find the pump flow, maybe it is too fast.
The bulb is clean, I removed and checked it yesterday, there was no build up.

One issue I found... I cannot see any UV light. At the inlet and outlet I have a section of clear pipe I have used to connect the outlet/inlet to my pump/pond hose (it was too big for a standard garden hose size and B&Q didnt have any adapters - I had to cut up my snorkel to make it). So its night now, and I can bend the clear pipe connector down a bit to look right into the UV clarifier outlet while the water is flowing. It is completely dark, no light at all.

Yesterday I took the bulb out to look and it doesnt look like its blown.

So could the bulb be faulty? Should I see UV light? I am not looking long as I know its harmful.

If you cant see the light the only thing I can think of is my flow is too fast.

Or am I expecting too much in 1 week? Should I give it more time?

Thanks for your replies.
  #13  
Old 07-04-2008, 03:38 PM posted to rec.ponds.moderated
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Posts: 366
Default How long does a UV clarifier take?

On Sun, 6 Apr 2008 11:10:53 EDT, lawr_1
wrote:

another question though... is UV light invisible? I just found one
website saying you can monitor the light through the inlet/outlet. I
thought it was invisible. If you can see it them my clarifier is not
emitting any visible light.


Even though we use the bulb for the UV, I doubt one can be reasonably
priced that is invisible. Mine emits a blue light. I did use a small
length of clear tubing on either side of the clarifier so that I could
see if the bulb is working and it shows up well at night. The UV
bulbs are sensitive to moisture in the chamber and mine blows a bulb
at a figment of the imagination.
--
Hal Middle Georgia, Zone 8
http://tinyurl.com/2fxzcb

  #14  
Old 07-04-2008, 04:18 PM
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First recorded activity by GardenBanter: Apr 2008
Posts: 8
Default

I checked my pump, its a Hozelock Cascade 1400 which pumps 1400 litres per hour, but the recommended for the UV clarifier is Tetra Pond FP 2500 which pumps 2500 litres per hour.

So it looks like its not to do with too fast a flow. I would have thought a slower flow means more chance of UV working?

So therefore should I see the UV light as there is none showing. Its the last thing I can think of, that the bulb is not working or something.

Thanks
  #15  
Old 07-04-2008, 05:42 PM posted to rec.ponds.moderated
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Posts: 93
Default How long does a UV clarifier take?

My bulbs glow blue as well. In bright (ambient) light that can be hard
to see, but it's very apparent in low light.

Dave

 




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