Fruits don't develop in my aquaponic system

[Ravi George]

Hi,

I am located in the south of India in Cochin. I have a 600 lt concrete tank with about 5o tilapia of different sizes. A pump works every 15 minutes to circulate water into a grow bed and to a 100mm dia pipe which is a NFT bed. Water in maintained at a pH between 6.8 to 7.3 and has a tendency to go alkaline very frequently. I manage pH with orthophosphoric acid. 

Fish thrive very well. I feed them with a home made food which is a mix of azzola, hen's eggs and bread. 

Problem is with the plants. First were my tomato plants. They grew very lush, flowered fruited and then all of them wilted one after and died.

Next were my peppers. They also did the same.

Another plant which is a local vegetable, has lot of vines, flowers but suffers from blossom blight.

I have a few okura growing, but not much of fruitng. Egg plants and corn are the same.

I have now am trying roses because they don't need to fruit.

Can someone guide me on what could be wrong?.

 

Regards

Ravi

[Ravi George]

Thanks.I was eagerly looking forward to your reply. Meantime, I started experimenting by adding turmeric powder with the fish feed. Turmeric also has a lot of potassium, I learned that the concentration is much more than in a banana.

[RupertofOZ]

I use Potassium BiCarbonate...  (available form wine making supplies).... the "bicarbonate" buffers the pH up when required... and the Potassium boosts the plants....

(Potassium BiCarbonate can also be used as a treatment for powdery mildew)

 

You can acheive the dual advantages above... by also using Potassium Hydroxide... but it's a very powerful buffer...

 

Maxicrop has a reasonable Potassium content... and many people just actually bury a banana into their grow beds... bananas have a high Potassium content...

[Ravi George]

Thanks Rupert. How do one give a Potassium boost....Organically?

[RupertofOZ]

You'll find most plants setting flower/fruit/seed.... benefit from a Potassium boost...

[Ravi George]

Thanks Steve and Patrick

The concrete tank has an asphalt paint lining inside. Maybe, the paint layer is broken at places. This could be reason why the pH isn't dropping by itself. The acidity must be reacting with the calcium in the cement which creates the tendency towards alkalinity.

However, if calcium is present in the water, blossom rot wouldn't be a problem.

To answer Patrick, I haven't checked the nitrate levels. However, if the nitrates were high won't it show up by lowering the pH?.

Ain't I confused??

[steve]

Hi Ravi, You might have better luck if you sealed the cement tank. Drain acid wash and seal with wax or paint. Some ideas here. http://aquaponicscommunity.com/forum/topics/alternatives-to-using-l...

[Patrick Fenton]

How are your nitrate levels?  High nitrogen will give great plant growth.  Lower nitrogen will help plants when it's time to fruit.  We cleaned our filters when it came time to fruit and it helped drop the nitrates a bit.  Found this especially true with tomato blooming and setting fruit.