Anyone try Nature's Domain Grain Free Turkey & Sweet Potato dog food from Costco? Our new pup's previous owners fed him Purina Puppy Chow (yuck!) and we notice his stools are pretty loose. We just bought a bag (about $30 for 35 lbs) of ND and are very slowly transitioning him from Purina. Wondering how long we should expect to see a positive change in his stools... Has anyone else had any luck with this brand?