Dont use Photo Flo with the Arista Kit. Instead buy some Kodak E6 Final Rinse. Very inexpensive, acts as photo flo to prevent drying spots, and also has anti fungal properties to preseve the film from microbe attack. Doesnt solve the color shifting issue though, only a formalin type rinse will do that. You can buy that if you wish from maco direct . de
They sell the Tetenal E6 Stabilizer (final) rinse. 1L concentrate to make 1000L, about $35
BTW, the Tetenal kit is much better than the Arista. Colors look as good as Kodaks kit. Arista color saturation tends to be very high, making skin tones look too saturated. And no Stabilizer / Final Rinse is included or even recommended (foolishly). Kodak kit is of course the best, but sadly no longer available, and its very expensive to buy the mass chemicals in bulk quantity now.