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