i was told after i was experiencing the same thing that they would go away on their own in a few weeks. it was driving me nuts, my pretty sand looked so nasty, my rocks looked horrible, and my glass was dirty.
however, just over time they somehow seemed to have depleted w/e valuable nutrient they required, i use tap water and they dont come back. im just dealing w/ red slime now and then.
i have added a phospho-ban bag to my sump, i dont know if it helps but its supposed to remove silicate from the water, its usage time is 6 weeks before replacement but ive not jacked w/ it for months.
your brown algae will go away on its own and be replaced w/ a new issue, as your gain more experience, more challenging problems will occur, and they become harder over time, strap on your boots and sit tight, the best you can ever do is keep your bio load as low as possible, that will give you luxury as compared to a high bio load tank.