I had no power for 11 days during Sandy. I prepared by using battery air pumps with the Pro V sponges already in tanks. I fed them after 7 days but slightly. The house was ice cold about 30 degrees so I covered the tanks with blankets and kept adding warm water every 8-10 hrs. My filters were off so as soon as the power was restored, I emptied them out, changed the media, and washed out the filter. I am aware of washing out the bacteria but the filter water was black and had a spoiled smell to it. I didn't wash out the hoses (too much trouble to unhook) and when I restarted the filters, the white residue came out. Is this harmful? What can I do to ensure the fish aren't poisoned from this?