Get reis minimap, its allowed on empireminecraft servers and it shows you which chunks slimes spawn in, another thing that might increase your slime spawn rate is to light up the areas around, above and below your farm that can spawn regular mobs.
It worked for me the last time i used it, this was before the 1.2.5 update though so maybe it doesnt work anymore or needed updating.
slimes are glitchy... my farm is from lvl 10-40 and 4 chunks wide....... was lots of fun clearing.... sometimes they spawn like crazy, sometimes nuthin. Decreasing the amount of places that hostile mobs can spawn (ie using water, slabs, or torches in the surrounding caves) increases the probability of slimes, but even then, its not guaranteed, its random. that function on reis minimap is intentionally disabled on EMC, using slime chunk finders is considered cheating as it gives an unfair advantage over other players.
The Rei's minimap trick stopped working after 1.2.5 - it is because the server stops sending the seed of the world you are playing on, or something like that. The issue with spawning, however, is a problem a lot of people have been having recently. It's most likely to do with the mob cap though.
The best way I find slimes is to make a diamond mine. You know, the ones that are like a 4x4 hole? Most every time, if it is fairly long, you will hear them. That's how I had my multi layer slime farms.... NEXT to eachother. Then the wild reset, and I never felt like making another.
To me this seems most likely the problem. Slimes are just glitchy and uncooperative, even the most complicated and large scale farms are not very productive, even if they are designed with what we know about slime spawning characteristics, they still dont adhere to spawning rules it seems. My slime farm took a long time and work, and it encompasses 4 chunks, 2 of which are almost certainly slime chunks, it has 4 layers that collect slimes and grind them down to the smallest size and brings them to a collection point... but even so, it still isnt that productive or reliable, some times slimes spawn like crazy, some times nothing at all.... i dont think ill be making another slime farm again either if there's another reset, it takes way to long and too much work and it only exsists for a little while before another reset comes along...
