Past pension purification


Hope this finds you well.

When i started my first job i was enrolled on a pension scheme. After about a year i logged on and realised there was an option of sharia fund. I didn’t know much about it at the time. However I selected it and didn’t think too much about it.

From the date i started to pay towards my pension + my employers contribution + tax relief to the date i selected the sharia fund. I have worked out the difference between this and the value of my pot at the time i changed over.

My question is of 3 parts:

  1. Would this difference be considered impermissible? It was on the default fund.

  2. If so, do i need to purify this amount only? Or
    The value of what was also generated using this amount (maybe a percentage etc)

  3. It is regarding my pension and i am well away from retirement. Can i purify my pension using cash I currently have?