Silicone cure time?

[Reef Pilot]

I would like to silicone a hook to the inside of the glass in my tank. That means I have to drain it below that level until the silicone cures. How long before I can raise the water again? I was hoping no longer than a couple hours.

I know they say it takes 24 hrs to cure fully. But I just want it to cure enough so that it won't poison my corals or fish. My tank will have to be disconnected from my sump during that time, and don't really want to leave it that way for too long. I do have internal pumps, so will some internal flow, and a heater.

I tried other means to attach the hook, incl crazy glue and even reef glue (probably the same stuff). It stuck fine to the hook, but not to the glass.