Today we did a lot of water changes and back washes in the fish tanks. We did this because the water in the big holding tank had heated up enough so we could replace it with fresher, colder water without harming the fish. All tanks need water changes at different times. It depends how many animals are living in the tank and how much food and waste is being produced from the particular animals. All water changes have the same steps, but some can be slightly different depending on the system. All water changes have 4 steps. 1- Unplug the pump, 2- Take water out of the tank, 3- Fill the tank back up with new water, 4- Plug the tank back in and make sure that everything is working properly. Also today when I checked my tank’s water quality, i saw that the nitrates had gone down. This is very good because it isn’t good for the nitrates to be too high. Too high a nitrate level would kill the fish. I think the reason that the nitrate level went down is because we replaced some of the older water with new fresh water. I really feel as though I have a good understanding of the nitrogen cycle in fish tanks now.