i bought a 60 gallon take with a 305 fluval filter, the idiot at the store told me i could put guppies in the tank within an hour. after rinsing and washing everthing throughly And getting the tank to a temp that wouldnt kill my fish I put them in its been a week, one guppy left of the 7 and 8 fries somehow survived being born since day one. My tank is a milky cloud slowly clearing ive used a product called cycle, how often do i change my filter carbon please explain to me about the 305 what should i be using whats bio and mechanical filtering I am confused I just hooked it up turned it on the water flow is on high. should i be doing a 15 percent water change every 2 times a week. and with my fluval do i need some type of airetion to provide oxygen sorry for all the questions just like to do my hobbies correctly exspecailly since In a week or so I will add more fish and could i get oscars in the size tank i have or no.