My tank is not that new..but I did just add more sand as my plant roots started going out of control..that could have caused it. Ok thanks! I guess my new shrimp won’t have to be fed cause they have lots of algae to feed on!Brown algae is often referred to as diatoms, it's common in new setups where water chemistry is unstable and even more so in those with new sand. Basically it requires silicates to reproduce, perform regular water changes, remove as much as possible and reduce your lighting slightly, it will burn itself out within a few weeks to a few months or so as the sand will become depleted of silicates to leach out into the water column.