Zombie's automatic farm

[SauBaar]

Hello, I want to make a zombie farm where zombies would fall from a high altitude and kill each other. My question is: How many grids must this "chimney" be tall so that it falls and falls?

 

[LordSidi0us]

I believe those kind farms have to be at least 50 blocks tall to work.

 

[JamieHamAndEggs]

for level 1 spawners, 50 would be safe, 40 is probably enough, haven't tested. for higher level spawners, adding 2 per level would be more than enough, but by how much idk.

 

[Justrepsaj]

with 25 blocks they will die but thats only lvl 1 spawner for higher lvl spawners i would sugest to use cactus with hoppers do make a automatic farm.