I was told that the rust colored algae is not algae at all. I was told that this is common in fairly new tanks and that they are organisms called diatoms. I got this information on the Oscarfish.com forum. I believe the person who wrote of this can be found under the name of Kmuda. My 125gt has only been set up since the middle of January. Supposedly it will eventually go away with excellent water conditions and time. Light is not supposed to be an influence on it, but to be on the safe side, I only leave my lights on for 5 hours a day. I have no green algae. That supposedly comes at a later time.