I have cycled my 46 gallon tank for 5 weeks with two giant danios. Two days ago I added two corys and then today I found out my nitrate and ammonia levels are high. I did a 50% water change yesterday before I tested the water. This was the first time I have used the gravel vac. I have been treating the new water with prime. I think I still need to do another water change soon because there is some food and stuff in the bottom of the tank that you cant see unless the water gets stirred up. How soon can i safely do another water change and what else should i do to lower the levels. Shoud i rinse the filter? Should i not use tap water to do water changes. And anything else that I might be unaware of since this is my first tank.