I have had a freshwater 10G tank for about a year now. A month or two
after I got the tank red algae (I assume that's what it is) appeared on
the sides of the tank and on the plastic plants (there are no real
plants).

I use a toothbrush to scrap it off the sides of the tank - it comes off
quite easily. Occassionally I'll take out the plastic plants and wash
them in warm water. Again, it comes off easily.

The tank has a flourescent light, though we turn it on infrequently
(15-30 minutes per week).

I've been trying an anti-algacide additive that I purchased at my local
pet store about once per week for the last month - no real help.

Here are some pictures of the tank:

http://www.deercove.org/fishtank.htm

Any help greatly appreciated!
Rob.