you want them to dry out a little. about 3" down should be bone dry until the next watering. It helps the root structure grow. Mine I only water about 1 a week until about week 2, as they get bigger there water needs are more. but tiny sprouts, don't drink that much.
As the top layers of soil dry it creates a tiny vapor barrier. (sorta). This means it will be dry at top and mud pit at the bottom of the pot. Root rot. you may need to transplant to dryer soil. Before those roots start to rot.
Also if you don't have one. go to wal-mart and get a temperature and relative humidity thermomter (digital) about 5 bucks
damn dude thats a major bummer. did you stick your finger in the dirt to see if it was dry like Mutt said? how close do you have your lights from your plants? what kind of lighting? these could all be factors in your plants condition.
IMO 5 or 6 inches away is to close for a 250 watt mh bulb. I use two 125 watt HIDS and I keep them about 12 inches away during the entire grow. Also, make sure you don't splash any water on the leaves of your plant as your watering, it water will magnify the light and burn the leaf very quickly. This is why I do not recommend foliar feed (spraying) for plants, unless you do it at the start of the dark cycle during 18/6 vegging, and never in flowering.