I use the Unicolor powder kit. With the first kit I used the stabilizer as-is and got white drying marks (interestingly, only on 35mm film, not on 120 film). With the second kit, I added 1/2 teaspoon PhotoFlo concentrate to 1 liter of stabilizer and it eliminated the white drying marks. I found I had to add another 1/2 teaspoon PhotoFlo concentrate after 10 rolls of film (I get a total of 15 rolls from a 1-liter kit).