Join Date: Jul 2013
Location: Chilliwack, Canada
algae never spontaniously appears.
some is gotten through the air, (spores and such)
most is gotten through spores in the water of the fish we buy.
like all the soaps on the market 99.99% effective, but it's that last fraction of a percent that is surviving that makes it into our tank, ... if conditions are right it grows and multiplies.
make a check-list of every algae (and the non-algae type algae) that your tank has ever had. for as long as the conditions are wrong, you'll never see that algae again. when conditions are right, you may suddenly have those same algaes showing up again.
if something dies off completely, buying another fish may reintroduce it, and if the conditions have been right for awhile, you'll have an outbreak ASAP