I never had any algae while my tank was cycling. And after it had cycled, I went for many months without any algae. The only live plants in it are floating plants and mossballs on the substrate. All the other plants are artificial.
Recently, back in March, I did two things different that have caused diatoms to appear on the glass for the first time: I put one of those vacation feeding blocks into the tank before leaving on a ten-day vacation, and I had trimmed back some of my floating hornwort.
Obviously, the first one added more nutrients to the tank, and the second let in more light. I have never had really bright light in my tank, which is a 20-gallon-high, Aqueon. I just have the single fluorescent bulb that came with it, and have always used that. It give off low to medium light, only.
I don't have a lot of diatoms -- just a few small patches on the rear and side glass panel. And a very small patch in the lower right-hand corner of the front pane. None at all on the opposite end pane. The places where they are showing up are places where the canopy of floating plants doesn't cover, and more light comes through.
I have read contradictory information regarding light and diatoms. Some have said they develop in low light and that brightening the light would get rid of them. Other sources have said exactly the opposite. Which is true, I can't say, except to describe my own lighting situation and what I now have in the way of diatoms.
Diatoms are harmless. They can be easily removed with a gentle scrubber during water changes.
I have well water, and I use gravel for a substrate. No silicates that I know of. If I had these, the diatoms would have appeared from the beginning. As I've stated above, my tank has been set up for many months, and only since March have the diatoms appeared.