suggestions please.

I have a new addition to the family its a180 gallon all-glass and I want to
install MH lighting over it. question is on all my tanks so far I use 400w
bulbs but want to try the 250's over this tank, but just cant bring myself
to do it.

I plan to use 4 bulbs @ 20KK without supplemental lighting. its what I use
on my 75 reef and I like it.

would the 250w's be enough light or should I go with the 400's.

thanks in advance
kc