Stress coat is fine. There are some that are better than others and more expensive. Alot of people swear by Prime. And i do not like it or its cost. But back to your problem. When doing maintenance just do filter or tank. Not both at the same time. It can be to much of a disturbance to the bacteria. But doing water changes and no vac'ing should not harm the bacteria as long as you are treating the water right away and it does not take you to long to do it.