Vintage tank -- Big sump

I've got a 125gal tank by All Glass Aquariums that been empty for 8 years. I'm thinking about using it as the sump for a 300gal. I have a few concerns though... how woried should I be about this thing leaking sooner than if I got a new (probably smaller:-/) sump. I would definately test it by filling with fresh water for several days before fitting it out as a sump. Also the tank came factory drilled with 4 holes in the bottom. I think that to use this as my sump, I'd have to install bulkheads and caps to close off these holes and then maybe drill new holes on the sides of the tank for new access.
The prospect of having a 125gal sump is really enticing but I don't even want to imagine trying to get that beast out from under the 300gal stand if there's ever a problem.

 

As far as it leaking......just reseal it before putting it together. It should only cost you a few bucks for the silicone and some of your time. as far as the holes that are predrilled.....I helped my cousin with his 125g and it had the same thing for some reason. We put in bulkheads like you said and plugged them up. We made sure to cover the plugged bulkheads with silicone, let it dry and then leak tested it. He's going on 4 years now w/o any problems;D

 

If you test a tank for a week and it doesn't leak, it probably ain't gonna start any time soon. You should be OK.

 

karma for the tip on siliconing the bulkheads. Resealing is an interesting idea but wouldn't that mean that I have to cut off all of the old silicone before I reseal it. That would really the labor factor on this project. Also I've seen how things looked after I did some silicone work on my turtle tanks. It got the job done but boy was it Ugly. If I could just reinforce the existing silicone with a new bead placed over the existing silicone this would be pretty easy. I'm not sure though... can you put new silicone over top of an existing bead?

 

When I did his......we only removed silicone from 2 corners becase they looked bad (was lifting) but besides that, we just siliconed over the existing. I laid down a few small beads along the whole tank so they wouldn't get out of control when I smoothed them with my finger.
just take your time with it.