G.E. Silicone I (not II) is aquarium safe. It used to be marked aquarium safe a while back,but has since been removed due to a contract with one of the name brands that is sold in Pet Stores for 5 times more. It is also marked "Windows and Doors ,100% Silicone, Clear. Sold at Home Depot. Empty the tank and thouroughly dry it. Scarape and remove all old caulk (since it leaked, might as well address all joints if one was deffective). Use good quality blue painters tape for clean edges. After it has cured, Fill it and check for leaks. If you can leave it filled as long as possible to help leach out silicates. 2 weeks would be good. It still will leach out silicates for a while , just not as much after the 2 weeks period. I will try to find a link later for better directions but thats it in a nutshell.

Great info. Hopefully I can get it back up for the arowana soon.
Thanks,

Try this one, LOL, the first step is deffinately the most important, and I forgot it.

Here is a link that might be useful: Leaky Tank Fix