Like this would be ok?
https://www.amazon.com/00688-Household-Waterproof-Adhesive-2-8-Ounce/dp/B000KE4PBQ/ref=sr_1_3?ie=UTF8&qid=1464809052&sr=8-3&keywords=aquarium+silicone
Excellent! Thank you so much! I really didn't want to order online, but I will if I really have to. I was just starting to get worried if I used something I wasn't supposed to.