Active foaming:
You need to heavily modify your printing settings depending on the temperature and setup to compensate the foaming expansion of the material when printing.
You need to print at very high temperature to achieve light weight results (~250_), these high temperatures will create a lot of defects on the print such as stringing and blobs.
At very high temperature, active foaming can achieve lighter print than passive foaming however the print may suffer of serious stringing defects.

Passive foaming:
You do not need to change any settings from your regular PLA settings (slight increase retraction) as PolyLite™ LW-PLA will offer light weight results even when printing at very low temperature (~190_C).
The lower the temperature the higher quality the print.

Hello Polymaker