We use a homemade powdered in our machine, and it doesn’t cause a problem. We use vinegar as the softener because we have hard well water, and for a bleach alternative, I use Baking Soda and Lemon Juice. Here is my powdered recipe:
3 boxes of washing soda and two boxes of Borax (that should be equal amounts)
2c Baking soda
4 bars of soap, grated or microwaved (We use Ivory because I usually get it for free or close to free. You could use Fels Naptha too, but we found that Ivory got the clothes cleaner. We also microwave our soap because it’s faster and….well, it’s more fun that way! Put it in the microwave for 2 minutes, let it cool and then crumple it up with your hands. It falls apart like powder.)
Mix it all together in a BIG bucket. This lasts us about 3 months.