Electrolysis of water with aluminum at the negative pole I am doing electrolysis of water to collect the hydrogen and I'm running into a problem: on the positive side I'm using graphite from a pencil (I cannot use any other material because it corrodes too fast) and on the negative side I was using copper. Copper was working really fine, the water was clear and no problem. But I don't have copper with a big surface area so I decided using aluminum (from coca cans) and my solution started to get dirty because of the aluminum and the aluminum is slowly disappearing. 

Why? Any other eletrode that I used for the negative pole was not corroded (only on the positive pole everything corrodes). Why is aluminum making my water dirty? Do you think if I use iron this problem will not happen?
If you are using salt to make the solution more conductive the process will cause the creation of Sodium Hydroxide, which will react with aluminium.