Andrew,

Molds and viruses are usually the hardest to kill requiring the highest
exposure to UV. Interesting enough, common ICH requires 336,000
microwatts-seconds/cm squared, which is one of the highest, while E.Coli
only requires 6,600. Most Pond sterilizers are set up for plain algae which
requires a lot less exposure. Even using an 8 watt sterilizer can be
effective and kill virtually any thing that is in the water as long as you
slow down the flow through the sterilizer. It may not sterilize a full pond
in an hour, but it could theoretically sterilize all the water in the pond
in a day. People seem to have a tendency of wanting to run thousands of
gallons per hour through a sterilizer and you can run 4,000 gph through a
120W sterilizer, but you are going to pay about $650 for the unit and it
will only kill algae at that volume. Many 8W sterilizers are rated at
600gph, but if you slow this down to 200 or 150 gph with will start killing
pathogens in the water if that is what you are after.

HTH

Tom L.L.
"Andrew Burgess" wrote in message
...
writes:

not really. needs a lot of UV to kill critters, a size most people dont
use on their
ponds.

This seems unlikely to be true for bacteria and virus, maybe for larger
parasites.

Kill, damage, slow down or just **** them off, its a positive effect ;-)

not to mention most of the cooties are found on and in the fish

All the parasites I can think of have a free swimming stage.

or the fish
poops or adhering to plants.

Fish poops in my pond are sucked into the filter, clear water out
of the filter goes through the UV.

Kills parasites, bacteria and viruses too.

I've never had to treat for disease or parasites, have plenty of wild
birds
introducing them and have always had UV. This isn't proof of anything but
still, I cringe when I see people post about dosing with antibiotics every
spring...