yeah, at this point with the light being closer I would definitely suggest switching to 18/6, I notice that when they get a good dose of light (and just watch your leaves, if they turn really purple and look bad, like they are slowing going to white and dying, then back the light off. .but not as much as you had it before.. just somewhere in between, they will get use to the light.. but it may just take them a little bit) I just moved mine down another 1" or 1.5" after having them about 4" away, and turned on all 4 CFLs now (100w eq. each) before they were turning purple and not looking too good, but most of them have a few sets of true leaves on them and are doing great..
as far as the ferts, I have a little bottle of indoor liquid ferts from MG, it says 7 drops per liter of water for each plant.. I take a.. well it's a really big water bottle and I think it's 1 liter, but anyways, I put about 2 drops of it in there, and do that every other watering, but with the warm weather, I have been watering most of them every day, mainly the ones that are right under the lights I give a good soaking and they dry up by the next day, the other ones I don't give as much water.
but just keep watching them, if the pics you took are right after watering them then OK, but if they are that wet all the time.. hold off on the water until most of them look pretty dry.. but they look really good.. oh and hold off on the ferts for the ones that don't have their first set of fully developed leaves I would say.. like the one in the first picture I would hold off for another week.. and maybe move it a little further back or away from the light until it gets it's leaves completely out
.. lol I just realized that I posted my last post wrong, I meant to say lower the plants, not the light.. but I didn't know that they were getting a little leggy.. and they seem to be doing great now, but take them off of the 24/7, and now that I look at it, it looks about the same height as mine, it's always hard to tell.. so the curling could have been a combo of water and light being on all the time, and if the ones in the middle that don't have any true leaves yet start looking bad and purpling more like the one in the first pic does (the first pic looks fine, but you can see it just starting to turn from a slight purple to a lite/whitish color almost, it's hard to tell) but if it looks worse than that.. move the light back down until they all have their first sets of true leaves... then move it back to where you have it now.. but just see what happens and adjust properly, but I would say watching the watering and making sure the tops at least dry out really well before giving it a good soak then