One assumes your talking about T-max or some
other t-grained film? The purple stain you see
is a sensitizing dye. It's normal to have a
slight residue after fixing but this should be
gone after using a hypo clearing wash agent. If
not refix. As far as refixing already washed and
dried film, it takes more than a hour for residual
silver to affect it. But if there's a purple stain
after both fixing and washing the film is either
inadequately fixed or you didn't remove all silver
thiosulfate complexes by using a hypo clear before
washing. Should also wash a good 10 minutes.

Generally as you use a film fixing bath you would
need to lengthen the fix time as you approach it's
maximum capacity. IOW if you fix the first few rolls
for 6-7 minutes you would need to fix the remaining
rolls for increasing longer times. Some people
recommend using a two bath fixer with t-grain films
like tmax, delta etc. to help insure complete fixing
and it would also reduce fixer byproducts. Whether
you do or not its a good idea to fix these films
for 3 times the clearing time instead of the normal
recommended 2 times the clearing time for non
t-grain films.

I use fresh fix for each roll. Add 20 ml of concentrate to whatever
solution volume needed to do one roll. Give 5 minutes with
constant agitation and take a look. Give another 2 or 3
minutes if needed. Toss the fix when done. Dan

I wouldn't worry too much about a bit of the dye remaining
in the film, but I would suggest moving to a two bath system.
I'm not an expert, so don't take my opinions as gospel, but I can
assure you that using a two bath system is easy and once you
get in the habit it is not significantly more work than a
single fixing bath.

The big advantage of the two bath system is that you can
be sure that you are fixing properly because the second
bath is always pretty fresh. You could also use fresh fix
every time, which wouldn't be as economical but would give
you the same assurance.  

Make up two bottles of film strength fixer. Label the bottles
"one" and "two." Use the fixer from bottle one for four
minutes (if using a rapid fixer, I use Kodak Fixer for six minutes
each bath). Pour the fixer back into bottle one, and then
use fixer two for another four minutes.

It is safe to inspect film after the first fix, and if the
fixer seems to be getting tired then discard the first fixer,
pour the second fixer into bottle "one" and make up fresh fixer
for bottle "two."  After a few cycles you should start over
with two fresh baths. I make fresh baths every time I finish
a gallon of fixer.

I get around 40 rolls per gallon from Kodak Fixer. I think this
is fairly conservative for a two bath system. You should get
somewhat more than this from rapid fixer. My bottles hold
around 600ml. I get 10-12 rolls from from a fresh first bath,
and around 6-8 from a first bath which was formerly a second
bath. If I am shooting a lot of Pan-F the fixer capacity seems
higher than this, if I am using a lot of Tmax-100 the fixer
capacity is less. Fixer is cheap, so if in doubt, change fixing
baths.

It may do some good to refix film if it has been less than
a couple weeks since they were fixed, but I wouldn't worry
too much about a bit of pink dye. It doesn't sound like
you have been seriously overworking your fixer.

Peter.

  Peter Irwin's advice about 2 bath fixing is a very good
idea. The capacity of single baths to handle tabular grain
films like T-Max is considerably less than for conventional
film. Rapid fixer is less sensitive to the residual
chemicals that come out in the fixer and lasts longer with
these films. Some say that a single bath is sufficient with
rapid fixer but I prefer to use a two bath system.
  It is impossible to give exact capacity for fixer because
the capacity depends on how much halide the fixer must
remove from the film. Its less where a lot of the halide has
been developed into metallic silver. The capacity is also
affected by Iodides and other materials which leach out of
the film, but its mostly limited by the amount of silver
dissolved in the fixer.
  The effectiveness of the fixer should be tested directly
by using a sulfide test on the film or on a sample of paper
processed through the system. One can also test for
dissolved silver by using a solution of Potassium Iodide.
This will precipitate some of the dissolved silver in the
hypo sample. If a could forms and does not redissolve in a
couple of seconds the fixer should be discarded. The Sulfide
test on the emulsion is a better test since it measures the
amount of halide left in the emulsion and its possible for
the Iodide test to indicate the fixer is still good after
its not completely fixing.
  I will post the formulas for these solutions below.
  Any unfixed halide, or the intermediate fixing products,
begin to change in a couple of weeks. Once this process has
begun refixing will not completely remove them.
  Michael Gudzinowicz posted complete explanations of what
goes on in the fixing process to this group some years ago.
His posts are still available on Google, a name search in
this group will find them.
  Test for exhausted fixer.
Kodak Fixer Test Solution FT-1
Water (at 80F or 27C)                750.0 ml
Potassium Iodide                     190.0 ml
Water to make                          1.0 liter

For use, to 5 drops of the test solution add 5 drops of
fixing bath and 5 drops of water. If a permanent precipitate
forms discard the fixer.
This solution will last up to 1 year in a filled, closed
bottle.
Note: This is a life time supply. I suggest making up 50 or
100 ml.

Residual Silver Halide Test
Kodak Residual Silver Test Soluton (Stock) ST-1
Water                                    100.0 ml
Sodium Sulfide, anhydrous (not Sulfite)    2.0 grams

Store in a small stoppered bottle for no more than 3 months.

To use dilute the above solution 1 part to 9 parts water.
Place a drop or two in a clear area of the negative or
print, preferably outside of the image area. Allow to stand
for 2 or 3 minutes and blot off. There should be no visible
stain.
  Note, if not stabilized this solution will eventually
cause a yellow stain. This stain is not indicative of the
presense of halides. There is a more complex version of this
test that stabilizes the test stain so that it can be
compared with a standard using a densitometer. This more
complex version is not necessary for routine testing. For
prints I suggest processing a test strip along with the
prints for testing purposes.

 I will give in addition the Kodak formula for a wash test.
This test indicates residual hypo.

Kodak Residual Hypo Test Solution HT-2

Water (deionized)            750.0 ml
28% Acetic Acid              125.0 ml
Silver Nitrate (crystals)      7.5 grams
Water to make                  1.0 liter

Again, this is a life time supply, make it up in 50 or 100
ml amounts.

Store the solution in an air tight bottle away from light
and excessive heat. It will last about 6 months. It will
cause black stains on hands or clothes if not removed
promptly.
To use apply a drop or two on an unexposed section of the
film or paper and allow to stand for about 2 minutes. Then
rinse the test solution off with water and blot. Even well
washed film or prints will leave a slight yellow stain.
There is a comparison chart in the Kodak book _The Kodak
Black and White Darkroom Dataguide_ Publication R-20 CAT828
9029  I believe this is still available. Kodak also used to
publish strips called Kodak Hypo Estimating Strips which had
a more complete set of comparison chips. I don't know if
this is still available.

  A 1:9 dilution of Kodak Rapid Selenium Toner can be used
in place of the 2% Sodium Sulfide test or residual silver
but is no longer recommended because it fails under some
conditions.

i wanted to thank everybody for all your replies. it will take some
hours to read and study them and i'm going to try all of this this
friday evening, that is the evening i usually spend in my darkroom.

have a nice day!