I have a 75gal s/w tank that is approx 4 weeks old. I was have a major problem with what I thought was brown algae. It was covering everything in a matter of days. The more I read on the net, the more I am convinced it was diatoms. I kept asking people for advise. They kept saying to be patient. It was hard because it made everything sooo ugly. I purchased a R/O unit with a DI
filter. Did a couple partial water changes with that. I was really getting fed up. Then one day, I noticed the brown was getting lighter. It has stopped all together now. I just should have relaxed and let it do it's thing. I am still cycling because my Nitrites are still up. Ammonia is gone though.