New algae on my sand bed!

[robbyville]

Hi gang,

For some reason over the past few days, I have been starting to get a brownish algae growth on my sand bed, it is almost always covered in air bubbles as well. I'm not sure if this would be known as a diatom bloom?

I have just cut my photo period down by an hour to see if it helps. I have not changed my feeding pattern at all, but my RO/DI reservoir water is reading around 12ppm (Just ordered new filters).

Any thoughts, will this be harmful to my system?

Thanks,

Rob