Yep, diatoms, and like Perfectdark said, it will probably get worse before it gets better
. Consider increasing numbers of turbo and Astrea snails. If the blooms gets bad enough, it can smoother corals by blocking the light
. Nonmoving/nonsluffing corals are more suseptable than others. Keep water changes going with RO water (that will help reduce nutrients and silica in the existing water); just don't change too much at once. Beyond that, all you can do is ride it out
. It will eventually get better. Good example of why not to use tap water though, thanks for providing it ~ sorry that it happened, but we learn from our mistakes. Experience is often a harsh taskmaster.
