Yellowing and Darkness/Curling

Here I am on my fourth attempt at a grow, not yet having made it past veg phase. I noticed the leaves on the plants were starting to get yellow spots, but one of the plants has dark contorted leaves now. The soil mixture and feeding schedule are the same for all the plants. I'm confused because I thought the yellowing might be an indication of a deficiency, but this other plant seems to be showing signs of too much of something.

Sickest plant (the only one out of 5 to look like this):


Other four plants:


Close up of yellowing of leaves on one of other four plants:


These plants are growing indoors. Grown from seed, about 3 weeks old now since they sprouted up. I'm using a 300 watt MH light about 2 feet above the plants. Temp at level of plants is 82 degrees F with humidity at about 38%. Light is 24/0. I have a fan blowing in cooler air and venting out through a tube from the top of the tent. Growing medium is 3 parts Black Gold Cocoblend soil, 1 part additional perlite (soil contained some), 1 part worm castings. Watering schedule is about once every 10 days (I have had problems overwatering in the past, so now I am waiting until the soil is very dry but the plants haven't started wilting). I'm using the General Organics GO box adding nutrients according to their schedule with each watering.

The thing I've done differently this time is water less often, run the lights 24/0 instead of 18/6, and use the GO box nutrients from the beginning. Normally at this stage my problems haven't started yet, and have had to do with overwatering and not providing nutrients.

Not sure what to do! Any help is appreciated!

10 days is too long. Every 5-7 days for a plant that size. Plants that size have no need of nutes yet, so adding nutes every watering is going to led to a 4th failure....

Is there anything else I should/can do to keep it from getting worse?

You have to think of each plant as an individual. What suits one plant won't suit another. Just water your plants for the next few weeks. Start with the nutes when the new growth starts looking pale green. The wilted one should correct itself within a few days to a week.

Thanks. I was surprised at how much the wilted one perked up just after 24 hours.