I currently have my fish in a 150 gallon tank and I'm looking to buy a 200 gallon tank 84×24×24. How would I go about transferring the fish from one tank to the other? I can't have both tanks set up at once so I'd have to drain the 150 and then fill the 200 in its place and put the fish in. Should I just take the gravel and water from the 150 and put it in the 200?