Scum problem in my pond - need advice

Tony Crabtree wrote:
Hi,

For the last couple of years, I have had a 100 gallon pond (moulded black
liner) where my Koi have successfully bred.

This Spring I have encountered a small, annoying problem. There is a furry
deposit on the sides of the pond - probably algae? that easily flakes off
and is being stirred up by the fish, forming a large amount of floating scum
daily. It is easily scooped up but accumulates a large amount of sludge
throughout the day. The pond water is clear as I have an ultra-violet light
and a filtration circuit.

The local pet store said snails and a sucking pond fish may help but the
water was too cold to use them, however now that the weather is warmer I
will give this a try.

I would be interested in any on-line comments or solutions if anyone else
has had the same problem.

Thanks, Tony
Vancouver, Canada