Mustard did you buy a micro tent?
You want an led in the big tent? If so then u going to have to go with at least the 500w. The 500 still has the 3w high output chips. The coverage area on the 500 is 4' x 3' though. But if your gonna be putting it along side a 400w hps, that would be plenty!
As far as the little tent goes, a 240w does an awesome job by itself! I don't use anything but led for flower! I love the 240 for my little, they make sweet love together and have beautiful green and purple babies! :grat: