Getting rid of brown algae!

Hello everyone,

I have been struggling with the spread of brown algae in my saltwater tank!
It is a 29g with 2 clowns, 1 yellow watchman, 1 pistol, 1 cleaner shrimp and several hermits/snails.
I already read some advice online, like here:
http://ift.tt/2rZLIoM

Also, from the petshop they told me to check my Phosphate levels and after I checked it is 0.

Is there anything else besides these tips that you can add?

Thanks,
Dimos