Actually i cleaned it first. about a week later i transfered all the stuff from my 29 *including gravel and most water* to this 40, the bottoms are the same size, the 40 is just very tall. So after i added water ect. i added my live plants and all that. it was set up for a couple hours and i added a couple fish. waited like 30-45 min. then added my other fish. This tank has the filters from my 29 gallon ank + the one that it came with. So i am not worried about filtration if that is what ur talking about.