Ok, I think I got it. Its quarter gallon.
I'll go away so I wanted to send my response for you to read before feeding them again.

This can be your problem combination with some other issues:
Half of the soil dry, half is wet. Some leafs have nutrient deficiencies. Some are trying to use that limited water for other purposes.

My suggestion is, spread your nutrients on all waterings instead of giving one time high and two times none.
First time, water them slowly with half or less than half dosage of nutrients until the water comes out from drainage holes. Don't poor all the water at once, give it slowly in 3-5 minutes. Assuming you have good drainage there with perlite and vermiculite. Each plant suppose to get about half gallon or 0.75 gallon at least before the water runs off. Wait until it gets dry, see the plants conditions. Takes 3-5 days to get dry completely. After that feed again like this. If they don't show any toxicity signs such as nuteburn set your nutrient level to normal dosage (spread the normal dosage on every waterings) and keep feeding carefully. If you see any nuteburn signs add one watering between feedings.
And another suggestion, your light distance is normal but its normal for normal plants. So, you raise your light up to 22-24" until they get back to normal. They don't have much water, they don't have enough power to take care of the light and heat. Let them rest a little. In 3-5 days you get the results and set the distance again slowly day by day.
Also be careful about the wind and the humidity. Don't let them dry.
tevfik Reviewed by tevfik on . Leaves Curling under / rolling Hi All, I have some rolling of the leaves Any thoughts? (attached pictures as well as survey) What is your experience level? Novice Your Equipment: .1) Type and wattage of lights? 400watt HPS .2) Distance from tops? 16 to 18 inch .3) Reflector type? bat wing Rating: 5