I won't dispute that brown diatom algae uses silicates to grow, but I'm pretty sure that all of our water supplies have considerabe silicates in it. And, ordinary pool filter sand is made up of quartz - silica. And, of course our glass aquariums are made of silica. Still, most times brown diatom algae disappears after a few weeks, even though we continue to change water, introducing more silicate. I don't know what causes it.