plants die after a fast growth

[Futti]

Hello,

I started my aquaponic-system in July. I cyceld the system with out fish. Everything went pretty fine. Since cycling is finished (begining of agust) I have constant concentations of 50-100 ppm for nitrate and almost zero for nitrit an ammonium. my ph is constantly betwenn 7.5-8. I use a aquarium with a volume of 80 liter

My problem is that several plants are dying after they had a fast growth. It happend for example with chives. And then plants like basil and thyme seem to stagnate in a hight of 4.0 cm.

Other plants like tomatoes seem to be more comfortable in my system.
It seems that the plants in my system have no strong roots. So when they reach a certain mass, they fall over.

I have attached to pictures which show chives.

Thanks for your help!

[Keith Rowan]

how deep is your growbed? it looks like the top layer of hydroton is wet? it should be dry for the top inch or so..
how big of an area is your gb? how many fish? what are you feeding the fish?

[Futti]

Hey thanks for your reply. my growbed is 30 cm deep and the water is only flowing unitl 5.0 cm to the surface.

the area of my grow bed is 590 mm*390 mm.

I have 5 young goldfish. I am feeding them with sth. special for goldfisch from the pet shop. the ingriedents are e.g. fish meal, wheat flour.

[Alex Veidel]

Could we see a picture of your tomato as well?

[Futti]

Yes of course.

Alex Veidel said:

Could we see a picture of your tomato as well?

[Futti]

Is it possible that my pH is to high (7.5-8.0) and so my plants could not get important nutrients like e.g. iron?

[Alex Veidel]

Yes, that is quite possible. What caught my eye was the plant in the corner (Strawberry?). Looks a little yellow.....is the new growth yellow with green veins?

Lower your pH and maybe add some chelated iron if you haven't before.

[Jim Fisk]

Could be damp off. I see what appears to be possible mold on the media in the tomato pic.

[Futti]

Thanks for your advices! :)

[JoAnne Bell]

Hi Futti!

Given everything you mentioned, I think you have a boron deficiency brought on by high pH. If you lower your pH to 7.0, I bet your plants will start growing again. Here's why:

Boron is essential for plant growth. It plays a role in moving nutrients, water and sugars to growing leaves and stems. It helps regulate hormones (including growth hormones). It, also, helps calcium movement (calcium's needed for normal cell development and division.). 

Since, a common sign of boron-deficiency is stunted growth. And, boron (and other micronutrients) is more readily available at pH's of 7.0 or lower. I think this is your issue.

How to adjust pH:

1)If your media has a neutral pH and your water has a 7.5+ pH, use a pH Down (such as food-grade phosphoric acid) to lower your pH.

2) If your media has a 7.5+ pH, then you will have to change your media to one with a neutral pH.

I hope this helps. Good luck!

JoAnne

[JoAnne Bell]

P.S. - I think your strawberries have spidermites. You may want to start treating them with beneficial bugs (spidermite predators) or sprays, such as Insecticidal Soap, Capt. Jacks or diluted Kapow.