Hello. I am a high school teacher. My class has started growing hydroponically for an agriculture course. I am fairly new to hydroponics. Last year I started tomatoes hydroponically for just a cople of months and had some success... getting to the green tomato stage before the school year ended. This year the leaves on all my tomato plants are looking pale and some are curling, dying and drying up (see pic). I have read that too much light and heat could be a problem, so I raised the light with no improvement. pH is around 7. I am wondering if nutrient concentrations are off, but I am following the recommendations from the hydroponic kit supplier exactly the same as I did last year with no issues.

A pea plant that i am growing in a separate tub looks poor too (see pic). Letuce and spinach al looks great to me, but the kale seems pale as well.

Does anyone think they may know my problem and how I may correct it?