I have 34 Fresenius 2008H machines. I have notice on a few of them that the tubing has become discolored. I have read that iron out will return tubing to its original color. How much iron out is used and how long do you leave it in the machines. Also is there a way to test for residual (maybe Hach test?)

I am interested in this too. Anybody have and answers

I have used iron out for years on different dialysis machines with good results.
Mix 3-4 oz of iron out to ea. gal. of treated water. I run the solution through the machine until the tubing is restored to its original condition. You can purchase a sulfite test kit (SU-5) from Hach to test for the removal of iron out.