brown coating

Question
I have had my 30 gallon long set about two months now. I have just noticed today there is a light brown coating on my skimmer pump and my live rocks have changed a little brown color, which were more a white color. I was wondering if my tank is going through a change right now. I have one cardinal pajama, two gobies, snail, hermit crab, emerald crab. So wondering if I should be alarmed

Answer
sounds like cyno bacteria, could be due to the ammount of nutrients your system is holding. try feeding less for a week and see how it goes.

also try upping the flow in your tank and aim it directly at the effected areas. this will keep it from settling.