Questions about some algae eaters

Greetings from Finland. I just joined this list, and now I'm going to
try to post here. Let's see how this works.

Ameca splendens, Butterfly Goodeid
I have a trio of them in my 150 liter (about 40g) tank. Has any of
you used them as algae eaters? Do they really eat blue-green algae?
The books I have don't mention anything about that ability, and have
different opinions about the right pH for them. Will they do well in
soft water, pH is about 6.8-7.0?

Bristlenoses, Ancistrus spp.
I have heard from the net and from my friends that they eat all the 
plants, especially Swords. Again, I have three small Bristlenoses 
and I have never found any holes in the leaves of my Sword plants.
They eat Limnobium and Duckweed, but those are meant as fishfood anyway.
What is the opinion of them here? Nice algae eaters or damned plants

Liisa Sarakontu                     INTERNET:    lsarakon at hila_hut.fi
Helsinki University of Technology   WWW homepage http://www.hut.fi/~lsarakon/