This invention relates to a process for converting silica to polysilicate gels or hydrogels by combining an aqueous silica source with a CO.sub.2 feed stream as the gel initiator, whereby the reaction stream is propelled at high velocity and turbulence maintaining the CO.sub.2 uptake rate in the reaction stream. The invention also relates to a process for converting silica to polysilicate by pre-carbonating water at pressures of equal to or greater than 100 psig before initiating the polysilicate reaction.