dwc auto

Hello, I've got a little problem here which is not caused by ignorance actually, I had to put my seedlings under 400 watt HPS in 4x4 (1.20x1.20) area, I'm expecting 600W MH bulb in several days (3 or 4) and I'll switch it as soon as I get it, I'll buy 600W HPS for flowering before my plants hit...