Quote Originally Posted by perkeleellinen View Post
Apologies for misleading, my wife's got some pH strips somewhere
Since the soup has plenty of color on its own, a pH strip used directly might give you a misleading color. Note, that if you dilute your soup, its pH doesn't change all that much (it's a logarithmic measure), so you can still test for caustic/acidic with 1:100 dilution of your original blix.