Ferroelectric lead germanate (Pb₅Ge₃O₁₁) crystals posess relatively large electrooptic coefficients and exhibit light induced conductivity. So far, only little is known about the photorefractive properties of these crystals. We present results on the growth of nominally pure and doped 531 crystals, and of 531 solid solutions. Basic parameters, such as dark and photo conductivity, are investigated in detail employing conventional and holographic techniques. Furthermore photorefractive parameters, like the sign of the dominant charge carriers involved in the charge transport and effective charge densities, are presented and discussed, also with respect to different thermal treatments after growth, which influence the determined parameters.