So today in the flat I was working in I noticed they had an empty dirty tank just sitting in the entrance, so I asked them what they were gonna do with it and they just said I could have it cause all there fish died and after spending lots of money on it they didint want it anymore, but what I wanna know is what should I put in it to kill anything bad that might still be there? I have removed most of the sand and scrubbed the side nearly clean but it started raining so had to stop, so what should I use? thanks
