about 2 weeks ago I found a small leak in in bottom seam of my 125 gallon tank. So I emptied it out dried it, sealed it, and filled it back up. It's been fine until this morning when I found that the leak had come back but a little worse . I know what you're thinking... But I though I could get away with just putting a crap load of silicone over the existing silicone . So what I'm asking is, is there a way to seal the tank from the out side, and is it possible that because it's not on a proper stand, that the bottom has to much pressure on it and it's causing the seal on the bottom to leak?
ps. I REALLY want to avoid draining the tank again , last time I had a 55 gallon sitting around that I could put the fish in, but I no longer have that.

Fortunately I have not had much experience with the leaking aquariums, apart from with a 30 gallon tank a few years ago, I was unsuccessful in mending that leak because I tried to repair the leak with the water still in place. To be quite honest, to do it properly you really need to empty and dry out the tank completely. how once you have mended and left it for a few days, then fill it up and hopefully it will be okay. But trying to mend an aquarium that has water in it is always going to be difficult.

Can you post a pic of the tank and where it is leaking? I have an idea!

Uhm, this is what i did 2 weeks ago.
I found that the outside bottom corner broke off a bit.
The inside of the silicone was still ok.
I vacuumed the corner and took away any loose fragments of glass.
Then i filled in the missing pieces with silicone and let it dry a bit.
I did a second thick layer while the first layer was still soft.
I flattened the outside with a wet finger and left the whole thing to dry.
The whole tank is sitting on a half an inch styrofoam and i took the risk for i know the inside silicone was still perfect and that I'd be watching the tank very closely for i had a new fish in there .

But after rereading your post i can only safely suggest to cut out all old silicone, reseal the tank and get a proper stand before you start the resealing.
There's no quick fix solution to your problem, and of one thing I'm sure in the hobby, your fish will ALLWAYS need water and leak getting worst suddenly, like at night,and the possible result of dead fish is surely gonna spoil your day.
Better being safe then sorry.

No chance of your LFS taking in your fish for some days while you reseal?
I often see fish on holidays at my lfs!

Buy a very large plastic container to put your fish, filters and heater in. Empty your tank and dry it thoroughly. remove the sealer and reseal. Its the only way to make sure you have done the job properly. Its not worth the risk bodging it, 125g of water will spread everywhere and you could loose your fish and the heater could break