Hydrometer readings

[mrhasan]

Yah I will but not until the end of August since I will be away for this whole month. My room mate will take care of my tank by feeding the fishes and doing a cup of fresh water top-off every two/three days. So just wanted to make sure that I am getting approximately correct results using the hydrometer so that I can tell him the interval of the top off. I always clean my hydrometer with warm water and vinegar after every use. Any suggestion?