Backyard Aquaponics
A place to discuss aquaponics

Hello,
my cucumbers show some deficiency at the bottom of the plants / the oldest leaves.
I'm not sure what kind of nutrience they need.

I feed peletts and the readings are:
Ammonia: 0mg/l
Nitrite: 0,1mg/l
Nitrate: 5mg/l

Added some pics of the leave...

Iron Deficency, Add Iron Chelates to the system at 1tpsn per 1000L, Have you added any Seasol Seaweed Solution to the system?? this could be an advantage as it will add some other trace elements and salts to the system.

Hi Tiggar,

1. How old is your system, ie: how long has it been running since it cycled?

2. What type of system is it, ie: how is the GB watered?

3. How long are the plants roots submerged in each GB Flood/Drain cycle?... (if using F&D)

4. What are your minimum and maximum water temp's each day?

5. What is your average daily air temp at the moment?

6. What is your water pH?

7. Are you adding Seasol, or a similar seaweed extract occasionally?... if so, how much and how often?

Looks like magnesium deficiency to me.

http://www.dpi.nsw.gov.au/agriculture/h ... -nutrition

Easy to fix my spraying a foliar spray of food grade potassium bicarbonate, generally widely available as an anti fungal for plants..

My first guess is that the plants feet are too wet!

Barring that, my next guess is Potassium, then maybe Magnesium deficiency as EB said.

Potassium deficiency will be more likely in a young system, but still possible in a mature system, especially if there are a lot of fruiting plants in the system. In the "Potassium deficiency" section of the link EB provided, have a look at the first leaf in the photo of three single leaves with Potassium deficiency, probably looks the most similar to yours.

If the root zone is cold a Magnesium deficiency will normally show before a Potassium.

Umm, yeah I meant Potassium hence my recommendation of "potassium bicarbonate"...

Good morning and thanks for your fast and lot of replys.

1. How old is your system, ie: how long has it been running since it cycled?
My system is two years old, but i'm stop in fall, and starts new in april.

2. What type of system is it, ie: how is the GB watered?
My system has two 500L gravel-gb with ebb/flood

3. How long are the plants roots submerged in each GB Flood/Drain cycle?... (if using F&D)
They have 15on/45off

4. What are your minimum and maximum water temp's each day?
min: 19 max: 23

5. What is your average daily air temp at the moment?
28°C

6. What is your water pH?
6,5-6,8

7. Are you adding Seasol, or a similar seaweed extract occasionally?... if so, how much and how often?
No i only feed my peletts.
I've added shellgrit for puffering, because my tapwater is low on lime.
It contains 2,8mg Magnesium and 19mg Calcium, so i need a puffer to prevent the ph to drop too fast.

We don't have seasol in Germany, so its difficult for me.
But we have a organic fert with only potassium (30% K²O) and magnesium (10% MgO).
At beginning of cycle i added to hands of epsom salt, but i don't know if this was already sucked up by the plants...


Greetings
Dom

Hi Dom,

pH and water/air temps are okay.

I would be making certain your GB is draining well in the 45 mins off, so the roots aren't staying constantly wet. The first signs of wet feet on most plants is yellowing around the leaf margins, and the leaf tip then the edges browning off, usually on the older, lower leaves first.

Potassium will probably be an issue, especially for fruiting plants if you are cycling the system from scratch every April... if so, then this means your system is only 2-3 months old in reality. Potassium may well prove to be an issue for you on an ongoing basis every year.

If you think it may be Potassium, for a more natural approach, Banana skins buried in the GB and the addition of composting worms to the GB will help, but will take time to release the Potassium.

For a quick fix, as EB said, Potassium sprayed on the foliage, or maybe a teaspoon added to your tank. You can use Potassium bicarbonate, Potassium hydroxide, and there's a food grade one that can be bought from home brew stores, I think from memory it's Potassium bisulphate (or metabisulphate)... something like that, ring a homebrew shop, they'll know what it is.

The addition of Potassium bicarbonate or Potassium hydroxide to your system will help with buffering also, don't know about the Potassium bisulphate, but I would imagine that would do the same.

Thanks for your reply.
But you don't think that it can be a magnesium def?

When i add potassium, i hope that i doesn't overdose...
How much i've to add?
The tomatoes and cucumbers flowers and have some fruits.
Some of the oldest smallest fruits of cucumbers gots yellow.


Dom

tiggar...not disagreeing with any of the above suggestions, but another thing to consider, cucs, along with other vines, drop their old leaves, looking a bit like ur pic there. Also there will always be a few unfertilised fruit that will go yellow and drop off

Check out this http://www.hbci.com/~wenonah/min-def/list.htm

Great link F&F

Thanks for your link and reply.
I don't see the different between magnesium and potassium def.
Both started with yellow borders, and intervenal browning.

Do you have some advise?
How often do you add magnesium, or how much magnesium contains your tapwater?

Thanks i have over 100 icons on my desk top with lots of info on it
[ thats why i have to have 2= 22 in screens ]

Create a folder on your desktop FF and drag all the icons/links into it. Then when you open the folder everything will be in alphabetical order