Thusly Geezer From The Freezer Spake Unto All:

Diatoms feed on silicates, phosphates and nitrates period!
You must have awesome lighting or none of the above in your
tank.

All aquaria using tapwater have the silicates, and most aquaria have
all three.

That silicates lead to diatom blooms is a myth.

I wish it did, because then it would be easy for me to get diatoms to
feed my shrimp larvae, but it doesn't.