Silica is a big problem for ...

Silica is a big problem for boilers, and filtration systems.  In Electrical Generation it is critical.  I have had a plant  manager run out to the parking lot and grab me as I drove in because he thought they were having a high silica problem.

If the water cycles up: the silica cycles up. At higher levels the  silica tests as OH alkalinity.  Thus, you can have no OH alkalinity present, but the titration tests shows that you do.   If you do not have a true OH alkalinity (pH over 10.5)  the silica will drop out.  This is important for dissolved silica.  Test for silica in the makeup water as SiO2.  If your test is a 20, you will probably have 200 with 10 cycles of concentration.  The silica can be helped to remain in solution if you have enough true OH added to the water, which a titration test will not show.  If you need to bring the pH down for final use, acid can be added after the UF.

If you don't have prefiltration now: get it immediately.  That is important for colloidal silica.  

Deposited silica forms a glass deposit that requires the use of hydrofluoric acid to remove - dangerous and deadly stuff to work with.  It can be done by using ammonium bifluoride  pumped into the system, and then adding HCL to form hydrofluoric acid: after use, that must be neutralized with caustic before discharge from the system.  Your arm can fall off if you touch Hydrofluoric acid, and you can die from touching a 10% mixture.  

This all depends on how large the system.  What are your water tests for the incoming water?  These types of tests should have been made before installing the system.  Somebody messed up.