So, hate to follow up on myself, but I just had a thought. It's possible
your "Anacharis" is actually not Egeria but one of the similar looking
(and illegal in the USA) "noxious weeds", Hydrilla and Lagarosiphon. You
can see some photos in the Fact Sheet section of the following website:

http://www.aphis.usda.gov/ppq/weeds/

Hydrilla is different from Egeria in that it has tubers on the roots, so
that's a good identifying mark. Hydrilla used to be common in the aquarium
trade until it became such an invasive species problem. Lagarosiphon isn't
supposed to be available in the USA, but that doesn't really mean
anything, heh. This page has an identification guide to differentiate
Hydrilla, Lagarosiphon, Egeria densa (what Anacharis usually is) and
Elodea canadensis:

http://aquat1.ifas.ufl.edu/seagrant/...html#lsconfuse

Note that it only shows the dark green, full nutrient form of Egeria
densa, not the stringy light green form I mentioned in my other reply. The
stringy form is somewhat similar to Elodea canadensis.

Here's also another page on the Anacharis confusion, written from an
aquarists' perspective. It also explains the difference between the
Egeria and Elodea genus (basically boils down to the flowers):

http://www.wetwebmedia.com/PlantedTk...dex/elodea.htm