I did not download, or load, or open the
link. I get nervous when something asks
me to do too much to see a picture or
information (this is entirely 'my problem'
and is usually solved when I can catch
youngest son...)

Substrate algae only means algae that grows
attached to a surface. There are many species
of algae that do this.

This is kind of a fun page
http://ihmp.net/@/vpl
or
http://www.microscopy-uk.org.uk/inde...ond/algae.html

I would worry about algae when the pond starts giving
off a bad odor, fish are gasping at the surface, fish
are dying or you have a daily appearance of scummy
algae appearing on the surface.

We can never get rid of algae and we don't want to.
But it can get to be a hazard to the pond when it has
too many nutrients - fish waste, rotting plants, too much
over all muck and runoff containing fertilizer.

kathy :-)
www.blogfromthebog.com