describe foggy, is it like so white hazy that you can barely see 5inches into the tank???? this could be a bacterial bloom. last time you cleaned it did you clean alot of it? maybe too much of it? i once cleaned my whole bottom sand not realizing i really messed up the benificial bacteria... make sure you test your water and see if there is an ammonia spike, (thats what the haze might be) if there is ammonia present, make sure to detoxify it using Prime or anything like it. make sure you do a 10-25% water change every day and dose with stabilize or Bacteria suppliment.