Silicates and Brown Algae

I think I finally figured out why I can't get rid of my brown algae after a
year and a half with this tank. My water department adds sodium silicate at
one of the town wells for "iron and manganese treatment and corrosion
control". They expect the SiO2 level at my house to be about 10 mg/l.

So, what should I do? (Now that I've got live plants and the leaves are
getting covered, I'm a bit more concerned about getting rid of the brown
algae than I was in the past.)
- Get an Otocinclus? (1 for a 10-gallon tank?)
- Get a silicate remover and try to figure out some way for my
Penguin mini-filter to flow water through it?
- Something else?

Thanks,
Dave