Hey, i'm no expert but it looks like you've got some
nutrient deficiencies and maybe some leaf burn from nutrient splashing.
For the GH nutes, you need to use them all in combination. Some people follow a 3-2-1 ratio for grow and then switch to a 1-2-3 ratio for bloom. if your tomatoes are indeterminate though, you may want to stick to a more even ratio of the three since you'll be blooming and growing at the same time.
For nutrient strength, 1 tsp per gallon of only GH grow is only gonna give you a PPM of around 120-150 depending on your water. that's pretty low. i'd boost that to maybe 200-300 ppm till it recovers. in general for nute strength, you only want to give you plant exactly what it needs, so ideally your PPM should be stable day to day, i.e. the plant is eatin as much
nutrients as water. if your nute level goes up, it means that the plant is drinkin more, so you should drop your nute level. if your nute level goes down, it means your plants are eatin more, so you should increase your nute level. do you know what your ppm levels are?
i've had one of those waterfarms, and its kinda hard to tell from the pics, but it looks like the nutrient solution maybe splashing the lower leaves and burning them. you can cover the entire top or turn down your air
pump if you can to avoid the splashing.
sorry for the length, but hope it helps.