Can you use powdered dishwasher detergent if you have a septic tank?

I know you're not supposed to use powdered laundry detergent, but what about powdered dishwasher detergent? Liquid dishwasher detergent just isn't getting my dishes clean, and I've tried using homemade detergent (Borax + baking soda + citric acid) and that's even worse. Can I use powder? The dishwasher is older and doesn't work as well as a newer one, but buying a new dishwasher isn't an option. Any advice?