Trouble with QT parameters

[navada718]

My qt tank was fully cycled in December.
Since then I've been having issues maintaining the cycle. MarinePure Ceramic Biomedia in the aquaclear 50, on top of filter floss. Additional bag of marinepur Gems Ceramic Media in the tank. I use microbacter 7, when doing water changes. Tips & recommendations are appreciated.

 

[living_tribunal]

Are you adding any source of ammonia for it? Bacteria can't live forever without sustenance you know...