Proper (memory) handling of TreeModels

["Matthew Yaconis" <myaconis nycap rr com>]

I have an application that, depending on a user's selection, filters the 
display of the base TreeModel (which is a liststore).  The way I've been 
doing it is as follows:

Program initialization:  The base model (basemodel) is filled with data.

During execution:  User selects a filter -> a new filtered model is 
generated with basemodel as the child and then a sort model is actually 
attached to the treeview for display, e.g.

filter_model = gtk_tree_model_filter_new( basemodel, NULL);
...
sort_model = gtk_tree_model_sort_new_with_model( filter_model );
...

There are many different views that can be selected so the above could be 
executed many times.  What is the proper way to deal with the old 
filter_model and sort_model?  Am I going about this in the wrong way?

I did it this way originally because it was simple and quick but now I'm 
refining my approach and realizing that this is probably leaking a ton of 
memory.

Thanks,

Matt