algae help needed

my tank is just about through its cycle i got one percula clown thats doing ok. fairly quickly my sand substrate became mostly covered in brown alomost like someone sprinkled dirt all over. it doesnt seem to be growing on any rock just the substrate and some spots on the glass. is this the brown diatoms that are normal? will it go away on its own i do weekly water changes and just yesterday hooked up a ten gallon refugium with chaetomorpha.

 

yea diatoms is normal, it will eventually go away on its own, i had mine during the first month and a half of cycling, next came the GHA which i'm currently batteling

 

i am also battling this GHA in my new 29gal Biocube, i turned my lights of for two days straight and it seemed to cut back alot of the algae. i have a bicolor blenny that eats alot of it and a small CUC for now. I had green hair algae bad in my previous 14gal Biocube and i just took out all the rocks and scrubbed the hell out of them, put them back and added Phoslock and havent had a problem yet! KNOCK ON WOOD