It depends on where the PAR is being measured, location (Height) of the Radion, light settings and a few other factors. In one case for example when measured directly under a Radion G4 the increase in PAR was over 100 but regardless of the area measured conservatively speaking a 10 - 20% increase in PAR (Or more) has been measured by stores and users alike. The real tell tale from users in general is the increase in Alk consumption after the kits are installed which indicates the corals are responding to the addition of the kits.