Backyard Aquaponics
A place to discuss aquaponics

Hi,

In my flood and drain beds, some plant's leaves are quite yellow. The veins on the leaves are green, but the area between the veins is yellow. The plants that it seems to be happening to: turnips, mint, courgettes. Is it too much water, a nutrient deficiency or both?

Some other information: the plants are being grown inside a greenhouse, tomatoes and lettuce are doing well, no yellowing.

Thanks Rob

Is it on the older leaves or newer growth, or both?

Hi, its mostly on the older leaves.
I just read a post about Iron deficiency, could it be that?
Also, where the leaves are yellow, between the veins, the area eventually dies leaving dead white area. It happens on the turnips mostly.

Thanks Rob

Sounds like potassium to me...

Could also be magnesium, Potassium usually starts toward the outer margins of the leaf while magnesium starts from the middle and spreads out both then turn to the dead spots but potassium might show a bit more scorching on the leaf edges. Potassium is usually more a brownish tinge while magnesium is more reddish but that may be a bit deceiving on turnips.
Wouldnt hurt the fish to throw a bit of epsom salts in anyway - it's often used as a fish tonic sorry don't know any rates.
John

How does you water test ?
Is it 0 0 0??
I think I would be inclined to increase the food rations if you water is
000.
Rather than adding suppliments

Think you'd be best doing a pH test before adding anything... if your pH is out... and you're locking out nutrient uptake, then adding supplements wont do much good...

Epsom salts are more likely to alter your "hardness" than provide any real nutrient supplementation... depending on pH...

Foliar feed with some Seasol or Maxicrop... and add some Celated Iron anyway... can't do any harm...

Post back your pH result please...

Haven't tried the epsom salts in Aquaponics
it worked well in my commercial hydroponics (NFT) setup on carnations and cucumbers both of which seemed to be prone to deficiency in tissue tests
Probably as the result of high potassium levels which is taken up in preference. Just had a look at some of my old notes - a foliar spray of 250gm epsom salts in 10 litres of water showed results within three days, this might be worth a try so you don't change your water conditions
John

Hi,
Thanks.

I haven't checked ph yet, didn't have PH pen yesterday. Will check tonight and post result.

Nitrites were really high all of a sudden, 2ppm from 0 at every other test. Nitrates ramped up to 45ppm (from 20ppm). Did 10% water change last night to try get the levels back to normal. Will also cut back a bit on feeding. Fish are doing fine.

I'm a bit confused as to why nitrites would suddenly be up though, the gravel should supply more than enough area for nitrifying bacteria. Is it possible that the bacteria died?

I will add some chelated iron tonight.


Cheers
Rob

I would agree with John


Check the nutrient deficiency chart I posted on the topic below.
viewtopic.php?f=6&t=6013

Hi, great, thanks. Looks like a cool chart.

Look at this chart, and looking at my leaves, it looks more like a manganese (Mn) deficiency. What can I use to increase manganese?

Thanks
Rob

Hi,

I measure water parameters again:
Nitrites down to practically 0,
Nitrates down to about 40ppm.
Ph 7.7
I applied seagrow(similar stuff to seasol) foliar spray this evening.

Cheers
Rob

I also notice that the bean leaves seem to be yellow between the veins too.

What should I try next?
Banana skins in the beds for potassium?
Chelated iron for iron?
Epsom salts to boost magnesium?
All of the above?

Thanks
Rob

The chart shows older leaves on the bottom going up to the younger ones. Since you had mentioned the yellowing was on the older leaves I am tending to think it is Mg. In any case if you are spraying Seasol or equivalent. - it should be alright since the composition says it has both. Check the links below.

Read more from the manufacturer: http://www.seasol.com.au/

Chemical composition: http://www.seasol.com.au/images/stories ... 7_2007.pdf

Please also check on the composition of Seagrow.