Aquaponic Gardening

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I have a three bed system, 180 gallon main tank with sump, and about 25 small Tilapia (were fry three months ago).  I am using 200 watt California Light Works LED grow lights (full cycle spectrum), but the set up is in a greenhouse and also gets ~ 3hours/day of natural sun light.  

My system cycled about six weeks ago.  My leafy plants are growing vigorously (basil, lettuce, other herbs).  I planted one 2' x 3' bed with 8 tomato plants.  The tomato foliage is lush and growing quickly. The plants are flowering, but there is little fruit set, and the fruit that does set is not growing quickly.  

I am wondering what I can do to improve the fruit yield on the tomatoes.  These are my ideas at this point.

- I suspect the system may not have enough nutrients yet to support fruit production.

- I could pull out some of the tomato plants to reduce density and load on the system

- My understanding was the lights would support fruit production, but I could go to a different spectra (this is an expensive option)

- The basic system chemistry is good, but I am wondering if there are supplements I should add (I keep pH at 6.8, I just started adding chelated iron)

- I am not certain how tomatoes pollinate.  They are in a closed greenhouse with minimal insects.  If they are not pllinating this might explain the limited fruit set, but not the poor fruit growth.  

I am very keen to be able to produce tomatoes with this system, so any advice would be appreciated.


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Tomatoes have "perfect" flowers both male and female parts in the same flower.try pollinating each flower in the morning when there open gently shake the branch the the blooms are on..two or three times a week. everyday if possible. I have seen people use electric toothbrushes to do this but shaking works well.temp of the greenhouse can have an effect on the pollinating process between 70 and 82 degrees is optimal. also anything over 80 percent relative humidity the pollen sticks together and will not pollinate well. I do not understand why you are using a grow light in a green house. why give a imitation when the real thing is available. Not that I am trying to be a A%% there may be a good reason I do not know about. fruit growth all depends on what cultivar of tomato you are growing. I have some Cherokee purples that seem to take forever to mature. Then I have some cherry's that seem to ripen as soon as the set....well maybe not that quick. your fish density seems to low for the amount of plants you have but that will change as the fish grow. others may be able to help you more. I am still a novice about the aquaponics side of this

David - 

Thanks for your reply.  I will try shaking the flowers to improve the pollination.  I assume that must happen naturally outdoors due to wind and insects.

I am using lights because the greenhouse is attached to the side of a townhouse in a north/south alley and only gets about 3 hrs a day of sunlight.  I think the previous owner of my home used it for plants that required limited sun.  I can't grow anything requiring full sun without using grow lights.  

It is a hot and humid environment, but not more so than I have seen work for tomatoes out of doors.


Nitrates may be an issue for you as your fish are likely producing more and more waste. Excess nitrate can be an inhibitor of flower setting and fruit production. What are your nitrate levels?

My nitrates are pretty darn high, and I've got more tomato fruit than you could shake a stick at. Barring some of the things David already 2 cents would lean toward potassium (K). 

Potassium plays a vital role in fruit set, growth and ripening. New systems can be pretty scarce in the K department.

8 tomato plants in a 2 foot by 3 foot bed seems like a bit much. 

These plants have been supplemented with both K and Mg

I've have three tomato plants in my system.  2 are of one variety which I can't seem to get to flower at all.  I can't figure out what is up with them. They are growing like wildfire but not a single flower. Any advice?

The other plant of a different variety flowered nicely and I pollinated them with a small paintbrush.  I just pretended I was a bee and visited each flower in turn.  A few days after that I had baby tomatoes.

I'd like to jump in with my own tomato question.  May I??  I have a Beefstake growing from Seed Savers Exchange, huge, beautiful plant with lots of big tomatoes... but they ripen so slowww.  And then they taste like crap (no pun intended!) and are mushy/grainy, just like a store bought tomato.  What's my issue?

Here's my specs:

Sunny Southern California

75-85 during the day, 65-70 at night

275 gallon FT with 2 4'x4' GBs and a sump

about 30 tilapia of various sizes

pH is about 6.0

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