Silicates are molecular Ions containing Silica bound with a metal. They are small harmless molecules.
Diatoms (along with other creatures) use Silicates to build their shell. Without Silicates Diatoms cannot survive. Diatoms are the microscopic alga that gathers on the glass and looks like dust when you scrape the glass. Most of the snails in the hobby live exclusively on Diatoms.
To remove Silicate from water you can use Reverse Osmosis to remove about 70% and then DeIonization to remove the rest.
Hair and most other types of nusiance algae do not need Silicates so removing all Silicates will have no effect on them.