My tomatoes have lots of green fruit but will not ripen.
If your tomato plants have lots of fruit that isn't ripening, it may be that the plant doesn't have the energy to "feed" all of them. Imagine a mother cat trying to feed a litter of twenty-five kittens! If your plants are loaded with green tomatoes, consider removing some to let the rest get more of the mother plant’s energy.
Tomatoes are a summer-time crop; the fruit needs warmth to ripen. If the ambient daytime temperature of the AeroGarden is under 70 degrees, you need to find a warmer place for it, or use a space heater (but avoid radiant heat!) to bring the temperature up. Not too warm - try to keep them under 78 degrees.
You might also try a 'Rinse and Refill' and empty all the water from the bowl and refill with fresh water and fresh nutrients. You can do this at every other feeding (once a month) to keep the nutrients balanced and give the plants a fresh water bath.