Thermometers, and cyanobacteria

About stick-on thermometers: I'm guessing their accuracy probably varies
most with the air temperature of the room. I keep my apartment and my
office fairly warm (70F or warmer); the heater in my tank at home rarely
comes on, and my tank at work is not heated (except for its lighting).

I recently compared two of the $2 variety of spirit bottom-of-tank
thermometers to stick-on thermometers I have on these tanks; they agreed as
closely as I could read them - to within a degree Fahrenheit or so. I
suspect that in a cooler room, where the heater would be working much
harder, that the temperature of the outside of the glass or acrylic would
diverge more strongly from the temperature in a more central location in
the tank.

Now, on a more APD-central topic, one dear to most of our hearts:
cyanobacteria. I am interested in treating a limited but up-and-coming
cyanobacteria infection in the small (10g) planted tank in my office. Is
there a consensus on which nutrients are typically limiting for
cyanobacteria? The articles on the Krib suggest that phosphorus is a good
nutrient to limit, as Cyanophyta can of course fix nitrogen. I will have
problems keeping the water nutrient-free: some of the plants in the tank
lose leaves almost as fast as they make new ones due to being outcompeted
for light and perhaps trace elements, and these leaves decay fairly
quickly. I am intrigued by the idea of using certain plants reportedly
allelopathic to cyanobacteria as treatment, but Hydrilla and Ceratophyllum
(the genera I've seen mentioned) would both be rather unwieldy in a 10
gallon tank. 

Short of erythromycin, which worries me in such a small tank, am I stuck
just vacuuming the stuff up and doing aggressive water changes?

In ex-flooded Seattle,