okay, so. i bought a 15 gallon not too long ago and ive been trying to cycle it, but its just too stocked. i have a male fancy guppy, female guppy, male dalmation molly, female creamsicle molly, male betta. i also have 5 baby guppies that were given to me free, i have in a 4 gallon container at the time being. i bought a 55 gallon! im so excited for my mollies to have the space they need and to be able to maybe add some really cool fish in the future. but, i want to do this right. not like last time. the 55 gallon came with a filter and gravel from an established tank of 6 years. my question is, since this came from someone i dont know (seemed like a nice guy) should i just forget about trying to use the bacteria and clean it throughly with hot water? or can i just fill it up with dechlorinated water and hope theres enough for it to be cycled/cycle faster? the filter is new, he said only two weeks old. if i cant salvage the bacteria or if its a bad idea, how should i go about cycling? should i put all my fish in? any advice?