Getting old fish tank up and running

Question
I have a 125 gallon 6 foot fish tank that has been out of order for a few years now.  The stone and everything are still in the tank.  It was running successfully for a number of years before some illness ran through the tank and killed about $1000 worth of fish.  I would like to get it up and running again but i dont know what the best/appropriate course of action would be to do so.  I know to completely empty the tank of the stone and all, but what type of cleaner would be most effective in making sure whatever killed the inhabitants the first time wont kill them again.  What would the steps be in refilling the tank and getting it up and running effectively with little or no problems.  I have a sand filter as well as two conventional filters that can handle 75 gallons.  I also have an ultraviolet filter which was running very well when the tank went down the first time.  I originally had African Cichlids from Lake Malawi in the tank and I am contemplating putting them back in or going a different direction, but still freshwater.  

Any direction on how to get my tank up and running again would be helpful.

Answer
Hi Mark
Nice size tank there!  Too bad on the previous disaster, that hurts.

Ok, what I would do in your situation,  because it's an older tank, and hasn't been used in a few years, I would remove the gravel/stones, take it outside or in a garage(hopefully it's not too cold where you live, or wait till spring time) fill it up and let it sit for a day or two to make sure it's not leaking anywhere.  Check the corners, especially around the seals closely for any leaks.  Better to be safe then sorry, especially with that amount of water.

If it doesn't leak, go ahead and drain some of the water out, and   honestly, if it's been empty all this time, whatever was in there is most likely dead by now.  But, you can use a mild bleach and water solution to disinfect it if you want.  Just be sure to rinse it thoroughly, and use a dechlorinator when you add the water-that should take care of any leftover bleach residue.  Vinegar and water is another good solution to clean, but not much for disinfecting.  Or just plain warm water is good as well.  Then just go ahead and set it up where you want it.  

Good luck, hope it doesn't leak!  Let me know if you have more questions.

Christy