oh mama, stop right there, DO NOT USE ANYMORE OF THAT STUFF!!!! let me just tell you what happened to me about 2 weeks ago. i was building my sump and used some silicon stuff from home depot that wasn't 100% silicon. i let it dry for a week so there was no chance it wasn't fully dry yet when i put it in. about 2 days after getting it up and running all the silicon was wet again and peeling off. i moved one of my dividers a little bit and a million little pieces of silicon got to the pump and shot up into my tank causing the deaths of my yellow tang and cleaner shrimp...they tried to eat it. it could be possible that your stuff is safe, but i got the 100% silicone made for aquariums at home depot too (didn't see it the first time) and you can be sure that is safe. i think there are very few things besides 100% silicone that can withstand being completly submerged in water 24/7. anyways, bottom line is i wouldn't use what you are using, i would make sure to get the 100% silicone. hth