there is some sort of brown stuff on my sand does anyone no what it could be
it looks like the sand just a darker rusty color

new tank? if so its normal for the first few weeks, and if this is not a new setup, your having water quality issues, how big is the tank and what kind of equipment are you using...filtratrion, lighting, current ect. how often do you do water changes and are you using RO water?

ok .............i think you need to do some serious reading on salt systems.............we will obviously answer all your questions but you need to get some good literature into you

pre-mix your salt water at least 24 hours before you use it, gives the salt time to fully disolve {or it can continue to climb if your "hot mixing" {mix it and use it right away}}

the brown stuff is called Diatom algae, it is a totally normal thing in a new cycleing tank, do more frequent water changes , like a 5 gallons twice a week until its gone, 2-8 weeks depending on your filter and bioload {how many fish you have}

i strongly suggest finding RO water {reverse osthmosis} yu can get it from most walmarts {culligan dispensers} i pay 33 cents a gallon for it

Boss