If the infos in your diary are right, you're burning them with your 30°c solution and 28°c substrate! Your root zone should be around 75°f / 24°c so try to get this temperature - or lower - for your solution. Plus, your soil seems very wet, it looks like you're overwatering them. As mentioned by our friend
@Athos, repotting in bigger containers could really help to prevent many troubles such as overwatering or root bound.