RBTA ISSUES after filter change

[mike31154]

9 months running the same media in the canister? Did you open it at all to clean it within those 9 months? If not, that explains a lot. Your BTA probably did react to a sudden, major water chemistry change if that's the case. If you're going to run a canister on a reef tank with full manufacturer's media in it, you'll need to clean it out frequently to prevent it from becoming ineffective & counterproductive. Like I mentioned, I run my canister (Eheim ProII) with empty baskets, save one, which has a small bag of carbon changed out about once a month. Looking at all the media included in your filter, if you don't clean the filter pad weekly, as well as some of the other stuff, things will slowly build up to elevate nitrates in your system.