Hi,
Blanket weed is a problem in my pond and i have seen devices on the
market that use variable sweeping frequency magnetic pulses to destroy
the calcium in the blanket weed. they use a wire wrapped around the
pipe of the pond pump so that all water that passes is supjected to
the magnetic field. one such device is at:
http://www.pond-equipment.creativefountains.com.au/Pumps/Blagdon/Blanket%20weed%20controller/blagdon_blanket_weed_controller.htm

as an electronics engineer, i wish to build one of these devices but
have not been able to find appropriate information on them or even
conclusive proof that they work at all.
I wish to know the specific frequencys that the "variable frequencys"
are and what is the speed of sweeping any other technical information
such as the type of circirtry used in comercial devices. how much
current is in the coil of wire etc..
Also is there any evidance such as technical papers to sugest that
these devices are more than a gimmick and are acually cappable of
killing blanket weed?

My guess is they are ineffective, perhaps a total scam. Try to find
engineering details on MRI = magnetic resonance imaging which uses a
very powerful magnet to put a spin on atoms inside your body. The
image is produced by the radio frequencies that are produced as the
atoms revert to normal spin. The MRI magnet is powered by a licquid
helium cooled super conductor. Doing it with copper wire might require
a dollar per second on your electric bill, and would heat the entire
pond perhaps 5 degrees c = 9 degrees f.   Neil

Magnetic devices purporting to prevent lime scale build up abound.
Similar thing on the page link. I?ve always thought them to be ?snake
oil? and what is telling for that device is the statement :-

?The device has a unique microprocessor which emits varying radio
frequencies through antennae cables provided.?

Binding with science. For microprocessor, read 741 or 555. If it *is*
a micro it sure ain?t going to be ?unique? other than it?s been
programmed. They?ve masked a processor! Yea right. That?s likely to be
in contravention of UK ?trades description?.

However, lacking absolute info, one cannot dismiss out of hand. But if
I bought every product which guaranteed 10% fuel reduction, my car
would actually produce petrol (gas).

You may have found the following sites, but if not......

Have a look at someone else?s view :-

http://budgetwater.com/articles.htm#Do magnetic water softeners work?

And follow links in this page for a different view :-

http://ecolodgical.yourhomeplanet.com/discuss_topic.php?topic_id=3

And for a variety of views :-

http://www.eng-tips.com/viewthread.cfm?qid=4423

Sorry about your weed problem but most of the products just chuck out
buzz words, don?t they. Can?t fool electronics engineers! Lots of hits
for "kill blanket weed", which you may also have found.

Best

Hi thanks for the advice guzzi, i would agree that the complexity of
the cirucits are proberbly quite pathetic and nothing more than a
voltage controlled oscillator. Here in the UK the comercial products
are about £60 which is stupid especialy when it is unknown if it
works.

In the UK, Maplin do a cheap and pre-assembled decalcifier kit that
might provide an affordable test rig.  I'd be delighted to know if you
have any success since I too have a pond full of green clouds.
http://www.maplin.co.uk/Module.aspx?ModuleNo=37766&&source=14&doy=8m7