This is an old thread (2012) but still relevant.
Milk is primarily minerals, protein, fat and water. It breaks down in water and causes ammonia. The easiest way to deal with problems like this (orange juice, cereal, milk, chocolate, etc) is with big water changes. Just change 75-90% of the water and gravel clean the substrate every day until it clears.
*NB* Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
You should also monitor the ammonia and nitrite levels and do daily water changes until they are back to 0.
Milk is primarily minerals, protein, fat and water. It breaks down in water and causes ammonia. The easiest way to deal with problems like this (orange juice, cereal, milk, chocolate, etc) is with big water changes. Just change 75-90% of the water and gravel clean the substrate every day until it clears.
*NB* Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
You should also monitor the ammonia and nitrite levels and do daily water changes until they are back to 0.
Now if she had added chocolate cookie crumbs , they probably would have gobbled them up 
