Brown Patches?

Finally my tank has almost cycled with only .5 Nitrite and going down daily
but in the past day brown patches have appeared and have started to spread
over everything and now the glass.

I think there Diatoms but I have seen mixed views on how to tackle this.
some say more light (which im doing), some say non at all.

Any advice from people who have actually had this and got over it? I know
lots of people will just give me advice they have read else where, Im after
past experience.

Many Thanks