ROX 0.8 issue?

[RussellHill]

I started running BRS Rox 0.8 in a Nextreef MR-1media filter a couple of months ago. Every time I change the Rox0.8 I get a cyano/algae outbreak a couple of days later. All other things/parameters being constant. Any chance that the Rox 0.8 is the culprit? Any thoughts appreciated

Russell

 

[RussellHill]

Bump

 

[twon8]

I doubt it. I've been using roc for years with no ill effects