Plants Staying Low

I am growing some Hindu Skunk and they seem to be growing nice. Growing nice but not up. They are two weeks into veg, have been topped and look like heads of lettuce.
I'm using Fox Farm Ocean Forrest, 1000 watt MH light in a Sunsystems Ocho light fixture on a light mover (only an eight foot wide room so they still get coverage when the light is on the other side). I have the lamp 18 - 20 inches from the canopy and the temp is staying around 68F - 77F at the canopy. Soil PH is 6.5. Do you think the light being close is keeping them from growing up? I'd like to get them about 15 inches before I turn the lights to 12/12.
 
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