Some of these filter aids are designed to create a goop layer in your sand filter, which is supposed to backwash out after you have filtered what needs to be filtered out, it's a short term thing, good for one pool cleaning. If you did not backwash, then this goop has worked it's way into the sand and created a bind with it, this will be really hard to backwash out now.
There are filter cleaners available, I don't know if they do what they say since i do not use any of them since I don't add unnecessary crud to my pool.

It might be worthwhile if instead of dumping more chemicals into the filter, you open it up, see if your sand has clogged solid, if it has, I would just replace it, I think it would be a better long term solution than dropping in more crud to try and "condition" it.