On the Wed, 31 Mar 2004 09:24:43 GMT, SjT uttered forth the following...
And how to stop the lining from creasing? (Does this affect the amount
of blanket weed if more creases are evident?)

Buy some Barley straw from your local aquatic centre and chuck a bag
into your pond. The water won't go green and it kills off the blanket
weed. As the straw rots it gives off bacteria that eat the blanket weed
etc.