Diatoms bloom periodically. generally whenever there is a high silicate content and extra nutrients not being taken up by other, more aggressive algae. This is why many people associate diatom blooms with the cycling process. They'll go away on their own, but can come back in waves later if the water balance is off. Welcome to the salty side! It just gets more interesting and colorful from here!
Someone stop me! Please! But... not just yet...
55 Gal Tropical FW
55 Gal Mixed Reef