Something growing on my LR

[borlaracing9]

I started to notice this orangish reddish color stuff growing on the top of my LR and not sure if its bad or not. I have had the lights on my tank on for the last 15 or so hours so maybe its just algae but i took a few pics. Any help would be greatly appreciated.

 

[SaltyTony]

Diatom Algae

 

[borlaracing9]

is that harmful to my tank? My fish seem fine since it started growing.

 

[Be2lose]

Read this.

About Brown or Golden Diatom Algae - What Makes Brown Algae Grow and Solutions for Eliminating This Problem in Saltwater Aquariums

 

[Kurt_Nelson]

Diatoms are a pretty normal stage a tank goes through when first starting it up. I'm assuming this is a new tank?

The 15 hour light cycle isn't helping matters, though. 10-12 hours is all you need, depending on what type of lighting you have. 15 hours is asking for algae problems down the road.

 

[borlaracing9]

Diatoms are a pretty normal stage a tank goes through when first starting it up. I'm assuming this is a new tank?

The 15 hour light cycle isn't helping matters, though. 10-12 hours is all you need, depending on what type of lighting you have. 15 hours is asking for algae problems down the road.

yep its a fairly new tank about 2 1/2 months or so. I left the lights off for the last 24 hours and did about a 20% water change and about 40% of it already cleared off my rocks so its looking better.