First off, what do you mean by "to much"? If you mean "too bright" that has nothing to do with diffusion. If you want to cut down on the power of the light AND also diffuse the light you can use one of the Elinchrom deflectors such as the translucent deflector in your sofbox. There are no grids or inner difusion panels available for the Portalite softboxes, but the deflectors work fine. A grid would not help with diffusion anyway, actually it would increase contrast. If you want to further decrease and diffuse the fill light (not the key light) then replace the D-Lite with a simple white reflector board instead. Do you have your camera set-up correctly, i.e lowest ISO (100) setting and a higher aperture setting (f11). I'm assuming that you are doing portait photography? Here's something else to try for portrait photography in a very small studio; switch off the strobe and just use the modeling lights.