Hi every one I am new in marine fish tank so I need some help. I have a 29G biocube tank and I have the tank only for two weeks and I have a lots of fish from my christmass presents I got 4 peliculiar clown, 1 clarky, cowfish(pufferlike) 1 2juvenile emperator and 1 pyjama and around 20pounds of live rock and also I got 1 tongue coral so my tank is packed. the problem is that the sand is getting like rusty colour in it; is there any solution for it cuz I have to dive my hand in to clean it.....one more question is my tank has too many fish in it? cuz I am thinking to get a mandarin goby and a blue tank