It's worth noting that Silica Gel is a fungal prophylactic, due to its desiccating properties. It is not a fungal treatment if you have an outbreak.
My airtight
lens box is 5-10% desiccant. I monitor its effectiveness with a cheap thermometer/hygrometer that I can see through the plastic box.
To be triple sure, I have some blotting paper soaked with p-chlorocresol, an anti-fungal, in with it. The p-chlorocresol was recommended (and provided) to me by a biologist in Australia who frequently sends research teams into rainforest environments with high-end microscopes. He says that they put strips of it inside the cases AND instruments (but clear of the optical path) and never have a problem with fungus.
None of this will obviate the need to have your lenses cleaned if they already have an infection.