This idea is just while your are worried about the droops...

You need a system of some kind...

you see...by hand watering you are basically, wetting the medium similar to an ebb and flow. I said similar. the difference being...there is no time on the ebb...meaning the fluid runs through the netpots and all the plants have to nourish themselves on is that little bit of salt residue.

you need them In something. that provides them with oxygenated moisture, at all times when lights are on...Imho

anyway, what I was saying is put an inch of water in the bottom of that tub, an air bar that will allow you to bubble...you need an airpump for this. fill it with hydroton...set the plants gently down into h'ton at fluid level...they should do fine like that for a few days.

Oh yeah. Put your hand right at top of plants...
move light towards canopy until you feel it starting to get 'HOT' back it off 3 inches or until your hand no longer gets 'HOT' and place a dedicated fan(not oscillating) blowing right between the 2 to cool radiant heat from lamp.
then repeat prcoess of adjusting the height of your lamp.

Leave them alone and make sure the little bubble tub does not dry out...

After a while they should perk up.

One more thing I noticed after rereading this today.

get off that 20/4 photoperiod....they might just be tired...LOL really; move to 16/8, 15/9, 14/10, (choose one) I think you will like what you see in a couple of days. lw