what is this white goo?

[luizflb]

Could you help with the identification? this appeared after starting to dose carbon and put on silicate remover media, could any of these cause this?
are only present in the filter compartment

 

[vetteguy53081]

Could you help with the identification? this appeared after starting to dose carbon and put on silicate remover media, could any of these cause this?
are only present in the filter compartment

Pics fuzzy to confirm but may be sponge formation

 

[luizflb]

Pics fuzzy to confirm but may be sponge formation

it is a silicate removing media, are sponges appearing on it due to the silicate concentration in them?