UV sterilizer and Filter Media
 

All my fish have died from ich so im starting all over agin, you know new gravel and water. Should i get new filter media that wasnt exposed to ich?

Also what are the pros and cons of a UV sterilizer, is it really worth buying?

what kind of tank is this? salt or fresh? i wouldn't remove the gravel or the water. you can leave the tank empty for a while and no ich will live. ich needs a host to survive.