I have a 55gal reef tank. While I was on a weekend trip my two year old managed to dump a whole container of pellet food in my sump. By time my wife noticed it was too late. When I came home the whole tank was destroyed. I checked perimeters and ammonia was greater than 8.0, Nitrite .25 and Nitrate 0. The tank was well established and had two clown fish, a yellow tang, turbo snails, hermit crabs, and some coral. Everything was lost except a few hermit crabs. Brown algae has taken over that tank. I am wondering what do i need to do to recover from this. My 4" sand bed has turned black in many spots. Do i need to replace the sand bed or will it recover on its own once a complete water change out it performed? Also do I need to replace my LR. It appears that all life on my rock is dead. Please Help.