Brown stuff

[Puppy]

keep getting this and don't know what it is or how to get rid of it

 

[oscarinw]

Looks from here like brown diatoms. Do a search for brown diatoms control and you will get your answer in detail.
However, a few quick ideas you might use are: increase the flow on the affected area, reduce the feeding in the tank and reduce the daily photo periods.
Best

 

[TheWhiteFord]

Yeah it just looks like diatoms which is completely natural in a reef tank

 

[Reefing Madness]

Diatoms. Once they've eaten all the silicates out of your tank, they will die off by themselves.