the absolute most effective way to get rid of it is to lower your nutrients. weather that means getting rid of some fish in an overstocked tank, feed less, get a skimmer, use RO water, do frequent water changes, or even buy some phosban and replace carbon frequently. haveing realativly new bulbs can help too. jsut as long as they arent super old. you can siphone a lot of it out during water changes and make sure everything listed above is in check and itll go away.