hi my name is Wes i have a 75 gal tank with a 30 gal sump protin skimmer and all what i need just get started with coarl and my question is i have fish in my tank its been up for about 6 months but i cant keep a tang alive had 3. 2 blue and 1 yellow i have checked all lvls are fine am i just this unlucky with the fish ??????? plz help