If I'm reading the instructions for that food, you should be closer to 3ml/L? You might just need to up the intake a bit if they are starting to starve? I'm just looking at the web for the fert info, so double check your label. 3-2-4 is not a bad balance really, adding 50/50% 3-0-0 would put you at an ideal 3-1-2 ratio. You don't have to act on that right away, just keep it in mind if you have any problems in the future that might be a lack of N issue like yellowing from bottom up. Your plant doesn't look too terrible, so just a light hand on the adjustments.