Lucky one peanut.
But when trying to stop a leak, you work from the pressure side, inside the tank!!.
You can do as Bill says, and if you have a crack form in the base as I have had, water leakage is fairly rapid.
I just moved back the gravel on the base, cut a piece of glass, slapped silicone all around the patch and put it over the damaged area.
It is still there to this day, and that must be ten years at least ago.
NEVER try to repair a crack from the outside of the tank as the water will just travel the crack to exit at the end of the it.
Alan 104