Trouble with German Johnson's

From the beginning, they seemed a bit weak in the system. I bought them as organic seedlings from Whole Foods. They just never seemed to take well to my aquaponics system, though they had 3 very large tomatoes (still green) on them. For the past week, they've looked weak and wilted, as if they weren't getting enough water. I tried giving them a little boost of nutrients, I tried pouring fresh water over their roots, and I tried cutting the water level down a little. Nothing - they remained wilted. I finally pulled them up yesterday, 'cause they simply didn't look like they were going to make it. The roots looked pretty rotten.

Doesn't make sense, as there are several other tomato plants in that same grow bed, and all are doing fine and producing fruit and looking healthy.

So, maybe it's just that German Johnson's don't do too well in aquaponics (or my aquaponics)? Or maybe I just had a couple of weak plants.

Will try them again next year to see if they consistently perform poorly in my system.

Update and a Reminder

First, the reminder:
- Once your plants are well established and large, you should check your drains periodically (maybe every 2 weeks) for root invasion. Roots grow very quickly and will spread throughout your grow beds. One of the best spots for a root to find is the drain, as it has a nice flow and a steady supply of nutrients. If you aren't vigilant, you may find that your drains have clogged with roots, and your grow beds will overflow.

Now the update:
See for yourself. Things are looking good. Tomatoes are large and healthy. Shouldn't be too much longer before they start to turn color. Some varieties are more prolific than others. Cherokee purple's are probably doing the best in terms of making the most fruit. Also doing well are the Amish pastes and the Brandywines. Not doing so well are the Pineapple somethings and the Moonglows, which only have about 2 tomatoes each on the vine. Not sure why this would be - it could be a great many things. Maybe they like a different pH? Maybe they need more or less sun? Maybe they need more or less water/nutrients? Or maybe they just take longer to get going?

Also, you can see that the yellow squash is repeating the feats of last year by showing MONSTROUSLY large leaves. It seemed at first that they were more normal-sized, but at this point, they are MUCH larger than the squash I have in the dirt. Also, you have to be careful to not leave the fruit on the vine too long. You go away for the weekend and come back to squash the size of bowling pins!