In natural fresh waters silica (mostly as ortho-silicates) are next
to carbonates in abundance. Possibly silica is also formed in a small
quantity as complex alumino-silicate ions. The major source of
silica is through dissolution of rocks in drainage basins. Silica is most
important in fish ponds because of its influence on diatom growth. Silica
is removed by plankton blooms and it gets back into water when diatoms die
possibly by simple decomposition.
