Why did you get a 400w and did you only get 1?
That Bluewave ballast is, I believe, a magnetic M59 ballast. According to Sanjay's site
, that bulb and ballast combo puts out a whopping 68 PPFD. FWIW, the 175w Iwasaki bulbs I use put out 71 PPFD with a magnetic ballast. In other words, that ballast and bulb combo sucks. It uses over 2x the electricity and puts out less usable light than what I use. Not to mention the heat. You may have heat issues.
Sanjay uses 400w bulbs over his 500g reef. I beleive he uses Giesemann 400w Marine bulbs
. They put out 209 PPFD.