Well, at least there is a definitive answer to the original question. It needs to be re-sealed now...
I'd do a bit more research before giving up on it. I seem to recall that a silicone that cures with ammonia as opposed to acetic acid is not necessarily a no-go for aquariums, as long as there is no added anti-fungal agent. Did they not at one time use arsenic for that purpose? They called it mold- and mildew-resistant, for use around bathtubs. If that's what you have, then you are indeed hooped.
Maybe next time...read the instructions before doing the build?