SAE's efectivness

     Are SAE's effective on red algae only, or will they touch thread
algae?  I recently had an outbreak of thread algae, or at least thats
what I think it is.  

     My 4 Chineese algae eaters have always done the job quite nicely,
but ever since I intensified the light and supplimented more for iron
I have been noticing spots on the acrylic.  It almost looks like dust on
the outside of the tank, but when you look close, you can see that it
is obviously on the inside of the tank.  Occasionally, I will see a
spot that the algae eaters missed and thin threads of algae are
growing out of the spots.  The treads are about .5 cm long.  
     I tried getting them off with an Acrylic friendly sponge I use
for cleaning, and couldn't manage to get the spots off.  
Question:Will SAE's eat this off?  They are readily avalable at the
local shop for 4 bucks. (I tried Ramhorn snails, and they
eat my plants like an all night salad bar)
Justin Frese
justinf at zimmer_csufresno.edu
Fresno, Ca.