You are supposed to discard the stabilizer/activator and never add it to the Glutaldehyde product. For Metricide brand, the activator is sodium nitrite, which is very toxic to fish. Nitrite is a reducing agent that is used to preserve meat. I am not sure why Glut needs to to be activated before its original intent use. Other brands use different activator that can be phosphate, acetate, etc but just don’t add it if you don’t know what it is.What is the stabilizing agent used in your glutaraldehyde product?
(eg, brown glass with air proof lid? especially helpful as this allows observation of any formed precipitates in which case, dispose as per legal requirements in your country)