Whitedeath

I don't know how to remove zombies spawning (streaming) close to me when i am walking around, i don't want this to happen because i will make custom spawn points for zombies (like hospitals and farms), but i don't know how to remove them spawning close to me. Do i have to edit zombies.lua and zombies_client.lua, or are there any other files that i need to edit? Thanks in advance.