Treats for struvite crystals in dog

I have a little schnauzer who is predisposed to struvite crystals. We have a good food and if we keep her urine acidic the crystals stay away. I am just needing help finding a good treat to give her that will not cause the crystals. We have been using grandma Lucy's organic pumpkin but which has never effected her but as of recently we purchased a new bag at she now has a crystal flare up. Don't know if it just had more pumpkin in it cause I know that is alkaline but I need something that I know isn't going to cause the crystals when I reward her with a treat. I have a Chinese herb that knock them out but I just have to make sure i am not assisting in bringing then back to my sweet little girl. Any recommendations is appreciated.