I know this isn't strictly a gardening issue, but the group FAQ didn't
have any pointers, so I thought I'd give it a go here and see what
transpired.

I have a largish pond in the new garden, about 11' radius and approx
2' deep, apart from a ledge about 1' deep and wide round the
circumference. By my calculations this gives me an approximate volume
of 4,300 gals or 19,600 ltrs.

Like the rest of the garden, this pond has obviously been neglected
for at least 5 yrs before we got here, and although there are a number
of goldfish (around 35 we think) and a small number of larger fish
(possibly koi - I'm no expert), they're difficult to see because the
water is a particularlt turgid green colour. I suspect there's a fair
amount of debris on the bottom of the pond which won't be helping.
There's enough plant life round the edges to keep the toads and frogs
happy, and a few waterlilies which bloom quiute spectacularly in the
summer.

Last year we tried Algo-rem from Tetra, and whilst we observed a
small improvement over the summer, the pond *really* cleared up during
the winter, but once the sun and any form of heat came back in spring
this year, we're back to the same green murk once again. I also have
some barley straw bundles which I was also told would help, but as yet
(2 months on) they're not looking very efficient.

Has anyone tried any of the pond vaccuums which you see advertised? I
REALLY want to get this sorted, and am willing to go to the trouble of
draining the pond if neccessary, but would rather not, so am looking
for other alternatives first.

Cheers, and thanks for listening. If there's another group that might
be more appropriate, I apologise, but I couldn't find anything from a
cursory trawl of Google.

Thanks again

Tim