Finally it is done. It took me and my husband 2 hours to clean the fish tank , wash the stone  and change the water. When we bought this tank 4 and half years ago, the sales person suggested us to change water every 2 weeks. Forget about it. Too much work, then we change the water once every  month, sometimes even one and half months. Too lazy. I remember  it cost 17 cents each to buy the golden...