PH is a little low, I would increase it to around 5.8 as this will allow the roots proper access to the macro nutrients it will need to overcome the stress, these get locked out if the ph is too high/low, you could also try something like Super Thrive which is vitamin-hormone liquid concentrate this will help your plants overcome stress just add one drop per litre along with your regular feed, they should start to pick up in a few days.