Thanks for the info. This was just a tiny little internal box to cover the siphon spout of a hob filter. It was maybe 2" by 2" by 4". That is why it was easier to just grab some silicon and try. Now I know never just something new without reading and researching. I usually use the small green tube of silicon we all use. I got this since it was in a larger bottle and had it for another project. Figured silicon is silicon. Big oops!! Other project was not for use in aquarium by the way.