Aquaponic Tomato Plants

I took a break from my aquaponics project as I was getting discouraged by seeing the previous batch of seedlings dying a slow death on top of my aquaponics plant tank. It seemed like I had missed some important point in the process of growing aquaponic plants, so I actually drained the whole plant tank, cleaned it, and installed a traditional filter in the fish tank / aquarium to keep the pet fish happy. That’s how fed up I was with my aquaponics problems.

… But I soon got too annoyed with the empty plant tank and my unreached goal of bringing this beast into production mode, so I went outside an started cutting side branches off my large tomato plants that I’m growing in self-watering containers beneath the south facing wall of the house. I learned from the ebook “How to Grow Juicy Tasty Tomatoes” that cuttings from a mature plant will easily grow into new plants if you stick the cuttings into the soil. Fortunately it works with aquaponic coconut fibers too:

The cuttings grew into tall plants, actually a bit taller than I have room for beneath the ceiling. The maximum grow height available in this system is small since the fish tank must be placed beneath the plant tank, and the fish tank in this case is an ordinary aquarium which you what to place on an aquarium table to be able to enjoy the fish without having to lay down on the floor 😉

A quick look at the new tomato plants gives you the impression that they are healthy, and the stems and leaves have a healthy color:

But if you take a closer look at some of the largest tomato plants you’ll find that some of the leaves have wilted:

(WARNING: Oldest aquaponic joke coming up: “I’m sure I gave them enough water…” Ha. Ha.)

I have to find out what’s causing this, and even the small developing tomato flower stems are affected by this too. The leaves turn dry and crispy and turn into dust if you squeeze them.

I wouldn’t say that the submerged roots look particularly healthy:

Rasmus noticed the same brown stuff on the roots of my previous batch of aquaponic plants and recommended adding air bubbles directly to the plant tank. I think it helped back then but I forgot to reinstall the air pump after I cleaned up the plant tank.

Lots of challenges still with this relatively new aquaponics home system in the corner of my living room. And I’m still having wet dreams about adding automatic electronic measurement of pH and conductivity.

8 comments on “Aquaponic Tomato Plants

  1. -

    I’m pretty sure that you need a lot more air and more filtering. I think the first step to check is if the brown stuff on the roots is the reason your plants are wilting- some people have had just fine plants with this, others can’t grow anything when this happens, I think the build up makes it difficult to get oxygen and nutrients to the plants. If you have watch Murray Hallam’s DVDs he makes sure he filters a lot before water gets to the rafts.

  2. -

    @Sean: Thanks for the tip about the DVD – I’ll have to check it out. I have no filter at all between the two tanks. It will be easy for me to reinstall the air pump, so I’ll try that right away and see what happens.
    Regarding a filter, I’m worried that it will act like an ordinary aquarium filter because the bacteria will live inside this filter instead of in the tanks. But okay, the resulting nutrients will flow through the filter and into the plant tank anyway. I guess it doesn’t matter where the bacteria live in the system then. The only problem is that when you clean the filter you’ll remove bacteria from the system, but there should be plenty living in other parts of the system so it doesn’t matter.

  3. -

    I am having the same problem with my setup. I am starting to believe that it is some how too much water. Should my roots be higher above the water? It was suggested to me that I put the roots 6 inches above the water and wrap them in wicking cloth (like cheese cloth). Any suggestions? Anyone have a better diagnosis?


  4. -

    @Mike: I can think of two things that could be the problem here, and yes, one is too much water. The problem I have is that the holes I have drilled in my EVA foam floats are too big, causing the net pots to sit totally submerged in water:
    My water is also constantly contaminated by coconut growing medium because of this. I would have to buy a new set of mats to change this, which is holding me back right now.
    I have seen pictures of floats made from 5 cm (2″) thick polystyrene sheets – I don’t think the growing medium is soaked in the same way as here, as the medium would have to suck up the water instead.
    Did you build your system according to a written guide or did you design it yourself?
    The other thing I’m working on changing, that could be causing problems, is the pH level. The efficiency of nutrition uptake by plants is dependent on the pH value. If you have a wrong pH value some essential nutrients might not even be collected by the plants. Murray Hallam uses lemon juice to lower the pH.

  5. -

    I have a rationale that you might be interested in knowing. If your plants are in the same container (i.e. sitting in the fish tank) then the brown stuff would be the fish waste. It’s not too much water. The waste blocks the roots from taking up the nitrogen elements produced by the fish (nitrates/nitrites). If your plants are not in a seperate container you would want to place them in one with a means of moving water from the fish tank to the plant tank. Research from the University of Hawaii and other locations here in Hawaii have shown similar results to yours. Good luck with your system. Aloha,


  6. -

    @Joby: I had separate tanks for fish and plants (the system has been dismantled now since I’m moving to a new house):
    I tried raising the pots above the water and let the roots develop down into the water, but the brown stuff still attached to the roots. I made a new filter which was very effective and placed it around the drain of the plant tank. I only tested it for a few days but I could turn out to be the solution in the long run.
    And still, I would like to switch to Leca stones, or something else, instead of coconut fibers – I’m pretty sure the fibers dissolve and contaminate the water.
    I have a very nice Eheim pump for moving the water between tanks:

  7. -

    I have 2 types of plants in my system, tomatoes and lettuce. There are 3 lettuce plants, 1 of them is almost white, but with a yellow tint to it, the 2nd is a light yellow/green, and the 3rd is a bright green. All 3 plants have browning spots on the leaves.
    There are 4 tomato plants. All of them have yellow leaves with darkish green veins in the leaves, purple stems and purple leaves close to the base. They also have some dying leaves. They are young plants, only 4-6 inches tall. please help!!

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