Hi @pym4742 ,
Do you mean the Capacity (set in the Initialize context) or the spawn rate (set in the Spawner context)? Capacity is immutable, so if you expect to have anywhere from 1 to 1,000 particles for example, you will need to set it to 1,000 as you can’t change that number outside of the graph.
If there is sufficient capacity, however, then you can expose a value to control how many particles you are spawning at runtime without having to recompile the graph: