//modify the main query for category pages
function td_modify_main_query_for_category_page($query) {

    //checking for category page and main query
    if(!is_admin() and is_category() and $query->is_main_query() ) {

        //get the number of page where on
        $paged = get_query_var('paged');


        //get the limit of posts on the category page
        $limit = get_option('posts_per_page');

        //offset is hardcoded because of big grid
        $offset = 5;

        // offset + custom pagination - if we have offset, wordpress overwrites the pagination and works with offset + limit
        if (!empty($offset) and $paged > 1) {
            $query->set('offset', $offset + ( ($paged - 1) * $limit) );
        } else {
            $query->set('offset', $offset);
        }

        //print_r($query);

    }//end if main query
}
add_action('pre_get_posts', 'td_modify_main_query_for_category_page');