does anyone have one of these? i have 4 tanks, two with these, no problems with the others, all have same substrate (half sand half gravel) the penguins keep completely stopping! i just pull out and re set the intake and it starts again. maybe sand, but the other filters dont do this. only had them about two weeks. was annoying but i thought it would go away. today i was gone about six hours, came home to a horrible smelling tank and dry biowheel. does this mean complete recycle or will the biowheel "regenerate" once wet? i romoved the fish to other tanks, did an 80% water change. tank is running again. by the way the ammonia reading before water change was dark brown off the chart and after a few minutes turned thick milky white....gross...i feel so bad...fish are doing ok now though in other tanks...sorry so long but should i return the filters as defective or does this sometimes happen....anyone have experience with this type of filter? *SICK*