Iam going to change to a bigger tank but last time i cleaned my tank i lost alot of fish. So could I have some advice on how to go about changing over, etc the filter gravel. Should i set up the new one and leave it running for a week then transfer the fish and old tank water into the new? Is it advisable to have an under gravel filter?
The best way to get a tank cycled quickly IME is to take some gravel from a previous tank and put it into the new tank, then keep it cycled with a few hardy fish for a week. After you get the new tank cycled, you can move your old fish in one or two at a time every other day