This post really isn’t cichlid specific, but it’s probably something overlooked by cichlid keepers just the same. If all of sudden you notice that your water appears to be cloudier than usual, it may just be that the glass needs to be cleaned. In addition to the diatomaceous algae that grows on the glass (the brown patches), your may also get a light film on the inside that will affect the appearance of the water. Furthermore, the outside of the glass needs cleaning occasionally too. A light film will also accumulate there.
So make cleaning your glass a regular part of your maintenance routine. It will make a difference in the clarity and besides, no one wants to look at a tank with brown algae all over it.