I’m struggling with what I believe are diatoms. It’s been a few months and my tank isn’t growing too well. With my water changes, I use tap water. What levels of silica in the water could affect this? I think mine is around 5 micrograms per liter.
I don't believe silica disolves out of glass but the sand will definitely add to it. In any case, keep cleaning up the diatoms till your tank matures, this can last for months. In the mean time try to keep your light intensity lower.