Tom, I'm not trying to dispute anything other than that the normal 15, 20,
or 40 watt UV units sold for ponds are not "sterilizers". The larger units
sold for home or industrial use for potable water WILL "do the trick", but
their wattages are considerably higher. And the flow rates are lower. So
there's a longer period of time that the water is exposed to the higher
wattage.

Personally, I haven't had to use my UV this year - so I don't have a problem
that needs to be dealt with (at least not at this time!). I turned it on for
3 days earlier this year when I had a cyanobacteria plague, but I knew in my
heart that it wouldn't work (and it didn't), so I shut it back down.
However, folks who have sick fish and think that a pond-rated UV will nuke
the responsible bacteria, or who run a UV and feel "safe" from bacteria, are
being sold a bill of goods: a UV with a 40 watt bulb and a flow rate of 3200
gph will kill the "green water" algae, but little else.

*That's* the point I was trying to make.

Or am I wrong? If so, I will gladly stand corrected - I'm still learning
every day, and faulty information should be corrected.

Lee


"Tom La Bron" wrote in message
...
OK Folks,

Here go again. You people seem to think that "Commercial and Industrial"
(C&I) UV's are better than residential units. C&I units are usually
Medium
to High pressure mercury type bulbs and are used for chemical byproducts
and
waste water or for the drying of printing inks, lacquers, paints and
adhesives. These units are not effective in germicidal action. The wave
length of the C&I units are in the 320 n and 440 n meter range, which is
well outside of the germicidal effectiveness curve for UV. Needless to
say,
the C&I bulbs are not used in residential units, mainly because of their
expense, plus they are not really any good for germicidal disaffection and
the amount of heat that they produce in production of their wavelength.
Also, something else to think about is that C&I units usually only have a
lamp-life span of about 1,000 hours, while low-pressure bulbs, depending
on
the manufacturers have a life span of 2,000 to 9,000 hours.

In my message on this subject before I told you that the germicidal range
of
killing UV was 265 n meters with the germicidal effectiveness curve being
between 250 n meters and 280 n meters. Low pressure UV bulbs are in all
residential UV devices and they put out spectral wave length of 254 n
meters of radiation, which is well within the germicidal curve and
relatively close to the max peak of 265 n meters. Low pressure UV are
the
only effective radiation units for germicidal effectiveness in the process
of disaffection. So you are grossly mistaken if you think that C&I units
are better, because they are not.

Lee, I don't know what you are expecting, but are you filtering your water
to the 10 micron range before it goes through the UV. As mentioned in my
previous message Turbidity does effect the UV effectiveness. You don't
have
to filter to that small, but any thing floating through the water and
through your UV will effect its effectiveness.

Oh, something else, are you a "salter of your pond." Guess what, UV
effectiveness is diminished by salt in the water.

So, I really don't know what your problem is, but it is not your UV,
unless
of course, you are trying to get more mileage out of your bulb that is
recommended by the manufacturer. They are like fluorescent bulbs which
actually decrease in output the longer they are run. Like I said before
their lamp-life runs from about 85 days to a little over a year. I am
sure
that if you look at your instructions for your 3-figure unit it will tell
you its lamp-life.

HTH, clearing things up.

Tom L.L.