I am setting dealing with the same question right now, but for a 90g setup. Both LFS's I've talked to said the Coralife 65 would be plenty because they overrate their capability so you'd probably be fine with the 125 if you go with Coralife (They don't carry the Remora's so they couldn't recommend them). Then I talked to someone at marineandreef.com which carry both and without thinking twice steered me to the Aqua C Remora Pro w/the Mag 3 pump which would also work great for your 125g. The more research I did online I'm leaning toward the Remora, seems to be a better built design but you may want to call them to discuss the benefits.