First Hydro grow 1000 watt hms, mh any suggestion

Wow first post in this section and come to think of it this is my first post havening to do with my hydro grow. .......

Ok I'm going to be growing in an attic as soon as my seeds get here. Its about 4 by 7 and I hope to get three plants going in a 66 gallon container (Might separate but if so one plant 20 gal side by side which would be just as good as the 66 from my measurements) I might get MH HPS 1000w for veg and grow would this support three plants? I know its a bit of a dumb question but I think no know it will with a 20.5 long 20.75 wide reflector......any help would be greatly appreciated.:thumbsup: