Sometime just have the location number in the Aquaducts (with its many levels and turns)can still be confusing. So to help a little...
Once in the Aquaducts make your way to Caraustam who is standing at the end of a T-intersection. From him, travel South, dropping down to the next level by either jumping over the water or going up the right side ramp and then down. Continue south toward the Obelisk and take your first right. This will be a deadend and the mediums are located there.
You will know you are in the right area because it you DID NOT go into the dead end on your right, but continued South you would be at the Obelisk and the Drainage hole. So if you find yourself at the Obelisk, turn around and go North and then take your SECOND left into the deadend.
The Location number of where you will make the turn into the deadend area with the mediums is 23687, 21106.
Edited, Jan 15th 2008 10:23am by Sorvendall