This is a generic answer.
Leaves curling down, top part yellow, and all leaf tips curling down with a little yellow starting at the tips (looks like the beginning of burn) is a sign of nutrient deficiency. your PH is right where it should be.
If you are watering every day, this is assuming that the soil is very dry each day, these are symptoms of rootbound. You will need to transplant to a bigger pot. My current grow I have a 2' plant it was in a 2 gAL. bucket. (wait...deja vu when reading your post). The leaves started curling and the top yellowed. I put it in a 3 gal. bucket and it perking right up. When I pulled it the soil was compacted and roots every where. It was stunting the growth and depleting nutrients too fast.
If you are @ 2' tall plants and in 2 gal. pots you are rootbound. for every 1' topside growth you need 1 gallon min. of pot size. I would get into at least a 3 gallon (5 gal. is the best).
I thought I would give you the two answers for the symptoms, but rootbound is your problem.