I am having an issue with Pagination on a custom Blog

I am having an issue with Pagination on a custom Blog Archive page. The pages and pagination links work but each page shows the exact same posts instead of the next posts in the archive.

<?php
$custom_query_args = array(
'post_type' => 'post',
'posts_per_page' => '18',
'offset' => '9',
);
$custom_query_args['paged'] = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
$custom_query = new WP_Query( $custom_query_args );
$temp_query = $wp_query;
$wp_query = NULL;
$wp_query = $custom_query;

if ( $custom_query->have_posts() ) : while ( $custom_query->have_posts() ) : $custom_query->the_post();
?>

LOOP CONTENT

<?php endwhile; endif; ?>
<?php wp_reset_postdata(); ?>
<div class="nav-previous">
<?php next_posts_link( 'Older posts' ); ?>
</div>
<div class="nav-next">
<?php previous_posts_link( 'Newer posts', $custom_query->max_num_pages ); ?>
</div>
<?php $wp_query = NULL; ?>
<?php $wp_query = $temp_query; ?>

Any help on this issue would be appreciated.

Thanks!