Andrew,

To correct something that "Ingrid the microbiologist," said, and she has
said this before and I can't understand why she keeps saying it, but she
says that "the UV roughs up the cell walls making algae clot and sending it
to the filter or to the bottom," which is a bunch of horse manure. The
germicidal effects of UV light involves photochemical damage to the DNA and
RNA within the cells of the organism. The Nucleic acids of the cells
actually are absorbers of the UV radiation and thusly the UV damages this
part of the cell inactivating it. Golly, you would think a "microbiologist"
would know that, instead of saying that the UV roughs up the cell wall to
make it clump, and if you don't believe me this information gleaned from
Paul Hundley with 25 years of experience and tons of degrees, who deals with
this stuff off the time in the aquaculture community.

Oh, while I am at it, turbidity is important, but if the UV sterilizers
didn't work on algae (actually a pretty large organism) and clear up algae
blooms, what Ingrid and Lee are saying it won't work on algae bloom, but it
does. The reason for this, for those who haven't thought about it, is that
the circumference of the tube that the UV light goes into is usually pretty
small and with the space literally taken up by the UV light it self, the
volume of area where the water flows through is actually relatively small
compared to the entire pond. Now, of course, the UV doesn't kill all the
algae as it passes through the tube, but it kills some and eventually kills
it all.

No manufacturer is touting one time pass killing of organisms when they are
talking about pond sterilizers, they are counting on the chance of
multiple-passes of water through the UV to get all the algae.

In public water systems that is not the case. They get one chance to
sterilize the water as it passes through on to the consumer thus requiring
megadose UV units.

Come people we are talking about recirc pond systems here not public demand
systems. Some of you are talking Apples and Oranges. Get is grip.

Ingrid also eluded to the size of the organism, I would just like to repeat
for those that didn't catch it in my message with killing capacity of UV
that algae is a big organism compared to most bacteria, so if it is killing
algae it will kill the bacteria also, especially if you leave the UV running
all the time, eventually it will pass close enough to be killed.

HTH

Tom L.L.
----------------------------------------
"Andrew Burgess" wrote in message
...
"Tom La Bron" writes:

UV sterilizers measure its light output in microwatts and the amount of
light needed
it measured in microwatts/sec/cm squared. Bacillus megatherium requires
only
2,500 microwatts/sec/cm2, while most other bacteria are in the 5-10,000
...

Ah numbers. Thank you thank you thank you.