Lots of brown stuff on the glass

[Gshiy]

so i have a 55 gal tank, i have not yet put any corals in, i only have fish but i have been getting lots of brown stains on my glass and sand, not sure if its a good thing or bad thing, i have also upgraded to a t5 lighting system, if anyone can help me out it would be appreciated

 

[skene]

ok... well before you really start asking questions like this... why don't you tell us a little about your tank. How old is the tank? How long do you leave the lights on for? What type of equipment do you have on the tank?
You do know that a little more info can usually go a long way.

 

[Gshiy]

ive had my tank running for about a year, i leave my lights on for hours at a time not really sure if that's good???