My mother has a 29 gallon tank with 6 or so various community fish, swordtails, tetras, platys, some sort of shark and a pleco. She purchased a 60 gallon tank and wants to upgrade. This is her plan. Fill new tank half with fresh water, dechlorinate and allow to sit for a day or two with a heater, to bring temp to the same as her current tank and airstone, to aid in chloramine removal. She then plans to use her existing gravel along with some new gravel, her current filter (which is large enough for the new tank), and as much water from the existing tank as possible. She will be checking water parameters daily. She is scared to death that there may be some problem with cycling considering 50% new water. In my pond experience, I did basically the same thing, just on a larger scale and everything was fine, but I'm not well versed on aquariums, so I'm not quite sure if they compare.

Geez, I hope that makes sense.

Thanks in advance,

Samantha