WaterBaby76,
About the crash statement, I have not found that to be true. I have been running my tank for over 5 years with an undergravels filter. (my wife says it has been over 10 yrs., how time flies when you are having fun.) I have not had any crashes yet, and have 0 nitrates. All I need is a lighting upgrade, (and more corals) other than that everything is well. If I look under the UGF from the bottom of the tank, yes there is some "silt/gunk", but I am sure that is normal.