Brown spot assuming algea ???

[etmtyll]

We are cycling a new 47gal tank with coral sand,and dead coral landscape we are in our third week blooms of brown patches are spreading what is it and is it normal.

 

[steve-s]

Welcome to AquariumAdvice.com

The algae you are experiencing is diatoms. Quite normally for a cycling tank. It will die down as the tank matures and the nutrient theat is feeding it (silicates) has been exhausted.

You can read about the different types of algae in the Articles section

What type of water was used for the initial start up? RO or other?

Cheers
Steve