Yeah i found the source of the leak. Looks like an already weak spot in the silicone was pierced through when gravel became lodged inside.
I re-did the silicone and followed the instructions for the waiting period before replacing the water and even waited a bit longer...
but i guess i should have either made a thicker seal or waited even longer!!
Tank was back in order and running when it began to leak again from the areas of new silicone!!!
so sad.... all that re-mixed saltwater gone except for about 25 gallons again.
I'm going to re-seal it with ridiculous amounts of silicone (and allow it to dry for an extra-long time) and sell or give the tank to a friend who wants to mess with it. Meanwhile, I'm buying a better and newer 75 gallon tank.