Nicole,
I have followed this thread with interest. I also shoot mostly TriX. And, in more than one format. In 35mm, there is no purple cast, but in 120 and 4x5 size (TXP320), there IS, in fact, a problem for me clearing the purple tint from the negs. I develop my own film as well. The first time I encountered this in 120 format, I let it sit in fix for quite a long time (>6 mins) and it persisted. Thereafter, I decided a presoak might be helpful, and so now, I do a 30 sec presoak of my TriX320 before developing. (I still have old emulsion TriX 400 in 4x5, and it's not like this at all).
Anyway, the presoak water pours out purple, and I have much less issues of the tint after the fix.
However, the stain does seem to fade with time, and a printed set of negatives on Ilford IV rc using a 2 1/2 filter gives pretty decent results.
It's too bad that when we get used to something in one format, that everything seems to change with the size of the film, but sometimes that's what happens.
I assume that you were using medium format with the purple results?
Have fun developing your own film. I sometimes thing I shoot film just to do the developing, but, I only do it for fun, so much less pressure....
-Tammy