Rust colors on rocks and crushed corral {new tank}

[jester8877]

I got my tank about 3 weeks ago its a 20g i have the lights,filter,bottom filter and powerhead...the basic setup. I added 5 damsels 2 days after i setup my tank. Then 3 days later I added 13lbs of live rock with corral already starting to grow. So ruffly 2 weeks later i have started to get a rust color alge or growth on my live rocks and just now, over night i got the same color growth on my crushed corral bottom!
So my question is this...is that normal? and if not what can I do to protect my rock and fish

 

[nero]

most likly diatoms... they are perfectly normal, but you want to control them before they overgrow your tank... maybe use less light and use RODI water... they will eventually mellow out after your tank has cycled. but just letting you know, you are going way too fast. you shouldnt add any livestock for at least a month, then maybe a small cleanup crew, then after another month or so ONE small fish. then add by the month. <--(IMO)
i would take back all of the damsels to your lfs, they will eventually die from either the cycle, or by killing each other anyways. not to mention, 5 fish is WAY too many for a 20 gallon. they also get kind of big. i would take them back as soon as possible before you get too attatched. besides, its cruel to cycle with living animals, you can cycle just as well with a piece of dead krill or fish food. just letting you know...
good luck with your new tank! do LOTS of research, and ask LOTS of questions. but two words of advise: BE PATIENT!!!
:happyfish

 

[nero]

gasp! i forgot one thing...
WELCOME!!!!!

 

[jester8877]

That was alot of helpful information. Although that was nothing that the 2 stores i wen't to mentioned to me. They suggested 3-5 damesls 2 days after i setup my tank. And the other store i mentioned that i just setup my tank and if it would be alright to put live rock in it, they saw no problem with it they even suggested 20-25lbs of live rock at $4.99 per lb... anyways just wanted to thank you for the helpful hints.
And bye the way i would like to keep the damsels till i get my tank established...then i would like to take them back maybe keeping one. Would that be not in my favor?
Thank you again. Jason