This noob still needs help

Hey all, just needed some quick help with my tank...


ok, i'm using your basic 20 watt bulb right now and have noticed a lot of brown spots within the sand, and a lot of stuff growing in the sand, not sure exactly what it is but itll be like small clumped up particles of something...whatever it is i know that theres a lot of stuff going on in my live sand that i wish would not be in there...

i also noticed at one point there was this thin black strand of something growing in the sand, it pretty much reminded me of venom growing in the sand...not sure what thats all about...

should I get a new bulb, maybe move into actinic lighting?
not have the lights on as much?

I notice if I leave my tank with no lights, my fish will stick to a corner and wont swim around as much, they just kind of stand still...

also on my live rock, i've been doing some reading and it seems as though cyano is growing on one of them...is this something i should be concerned about?

also on just a bizarre tendency my nemos tend to stick to one spot in the tank and they like to move the sand out of the spot they like to stick to, does this mean something? i've covered up that spot with the sand about 4-5x now and when i come back later i'll see them waiving their tails and getting back to the way it was how they liked it...

 

how old is the tank

 

also what are your water params

 

also the nemo thing is normal as far as i know mine use to do it they flick the sand around and they have moved tank for about the 3rd time now and there fine

 

Size of the tank with a 20 wat bulb?