casting Request.Forms to string?

I'm calling a method like this:
DataTable dtModifiedData = detailsGrid.GenerateRowColumnDataTable(Request.Form)
The GenerateRowColumnDataTable method retrieves all form variables with <input> tags.  My problem is that my columns are named in a strange format like this:
#X#_G1_NAME_1    so when I look at what's being rendered I see %23X%23_G1_NAME_1   so I thought I could use Server.URLEncode() around Request.Form but I'm getting an errot that it can't be converted to a string. What would you do in this case?
Thanks

 
...