I've never been big fan of big external pumps on closed loops. I think even one WP40 would be sufficient for a 120g. I have a single WP60 on my 6' 165g and its turned down to lowest setting. Of course I'm not full-blown sps so that setting great for LPS heavy system. I could push water on my floor easily by upping WP60's flow to highest but that's just silly
