Adding on to the thread inchworm directed to. Quite a lot of adhesives are plastics but that doesn't change whether they are safe plastics or not to use in an aquarium. PVC leaches chlorine rapidly for the first 2 weeks of being removed from a packet and then continues but at a much reduced rate e.g. that smell of a new plastic shower curtain/ table cloth ect. is a release of chlorine whilst safe for humans it could kill ADFs which are particularly chlorine sensitive.