Use the juwel black silicone to fit your juwel background into your aquarium or to fix your juwel filter boxr instructions for user r 1 remove the cap from the tube and screw on the nozzle cut off the tip of the nozzler 2 take care to ensure that the surfaces to be cemented are absolutely clean and dry before applying the siliconr 3 a dry skin forms on the surface of the silicone after just a few minutes the silicone is firm after approx one hour wait for 24 hours before filling the aq