Backyard Aquaponics
A place to discuss aquaponics

Hi All,
i would appreciate any help any one could provide.

This morning i went out to have a look at my NFT and all the bok choy and Kale has turned Yellow. This has happened overnight as i checked on everything yesterday. The bok choy in the greenhouse does not seem as Yellow but has a slight tinge to it.

My system is reasonably new about 2 month's will attach photos. Everything has been going great guns and the water test results have been really steady.
Ph:7.5
NO2:0.05
NO3: 5ppm
NH4: <0.05
FE: 1.5+ (Added some iron supplements in about 6 weeks ago)
Kh: 3d x 21.8
PO4: 1.8+


These have not change much from about a month ago and have tested every week.

https://photos.app.goo.gl/sqEt65UwB7TqKH5X7

Looks like nutrient lockout from the high PH. Does not matter how much good stuff is in the water, the plants can't eat it.

You can foliar feed while you wait for that PH to come down.

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Thanks for the reply any particular products that you could recommend, i was think seasol or powerfeed something like that?


https://www.seasol.com.au/home-garden/products/seasol/
https://www.seasol.com.au/plant-food/pr ... powerfeed/


Thank heaps for the help cant say i have ever foliar feeded before.

Go with the Seasol. In my dirt garden I will use what ever I can get my hands on. But for the aquaponics I only use organic and natural things to protect my fish.

On this side of the pond we don't have Seasol and some chelated irons are hard to find. Any Kelp or Seaweed extract will do fine in the water or as a foliar feed. Great source or micro nutrients and potassium and is fish safe. Most stores have it in stock for those organic nuts.

Iron can be foliar feed or added to the water and too much of the wrong type is poisons to fish. At that high of a PH and depending on sunlight it may best to foliar feed that. Once it hits the water it is PH locked out quickly and after some UV exposure it breaks down the chelate. So it probably best to foliar feed that.

I am not an expert on nutrient defiency but iron and potassium are common defiencies specially in new systems. It looks like you have an iron defiency. There are a lot of defiency though cause chlorosis.

Trying to bring down a PH feels like a loosing battle and winds up being expensive. That reminds me, on pay day I need to pick up some humic acid. I been meaning to experiment with that. Should bring down the PH and is an organic chelate that is fish safe.

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thanks heaps will go down and get some tomorrow will let you know how i go.

Thanks again

Also, what's your flow rate like? I turned the flow rate up on my towers and noticed an improvement the next day.

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sorry for the delay, tested the NFT today and I am running it at about 2 litres / minute.

What type of iron supplement are you using?

The earlier comment about nutrient lockout due to the pH is probably what's going on and the nutrient that is locked out is most likely iron (it's very common in AP and the newer leaves are the ones showing chlorosis - that's a pretty good indication that it's an iron problem). Many types of iron supplements are not available or have limited availability to plants at that pH. The iron chelate Fe-EDDHA could be added to the water (because it is available at that pH) or you could spray apply other types of iron (usually there are some instructions on the package for spray application). Spray application gets around problems with the system water pH. Iron is not particularly mobile in plants so they don't shift it from old to new leaves very well.

I don't usually think of the seasol products as an iron supplement so I want to take a look at the analysis. I'll likely post up again in a bit.

Regular Seasol will work, I definitely wouldn't use the powerfeed version it's better for fishless cycling or operation since I'm pretty sure it has ammonia that could be bad for the fish. The Seasol contains iron and will eventually green up the plants but other iron supplements could get the job done faster because they contain more iron and are specifically for adding iron. I'm not suggesting using this but I noticed Seasol has a lawn product and it has lots of iron for greening up the lawn compared with what you'll find in regular Seasol.

thanks for the responses, i have been applying seasol via spray for the last 3 days, not much effect but will keep at it.

Is it worth trying to lower the Ph with some form of acid?

How many fish do you have and how big are they?

Don't see much in the way of fish and this is important because it affects the feeding level. The bacteria are being fed by the waste from the fish and it's their biological process that lowers the pH. From the looks of things it may take a while for the pH in your system to come down but it will eventually come down on it's own so you don't need to adjust it unless you just want to.

You have a couple of choices.
1. Leave the system alone and go on as normal but with iron supplementation using something like Fe-EDDHA until the pH comes down on it's own.

OR

2. Treat the top up water with Hydrochloric acid to reduce it's pH and gradually use this to bring the pH of the system water down to where the iron already in the system is available to the plants. You might still need to supplement iron if there isn't enough in the system. Changes to the pH need to be gradual - no more than 0.4 pH units at a time to avoid stressing the fish.

If you already have the hydrochloric acid then it's tempting, otherwise I'd just skip acidification and get the Fe-EDDHA, your system pH will come down soon enough on it's own and you'll likely need iron supplementation in an AP system anyway.

It's important to chose the right iron product because many of them will not be available at your pH. If you get the wrong one you can still use it but you'll have to spray apply to avoid the pH lockout issue.

Thanks again for all the replies,

I currently have 8 Gold fish probably around 5-6cm and a couple of yabbies. Just about to stock with 12 Silver Perch next week but since all this I am holding off.

I do have hydrochloric acid already at home and am very tempted. Day five with the Seasol still no major improvement, so I will order some EDDHA tonight found some on Ebay unfortunately 5 days delivery.

am due to add some water in so might try a slight adjustment tonight see what happens.



Thanks again

I agree with Scotty.

Have you tried to foliar apply the Iron?

Those things you add to your water will also affect your PH.

Yes have been using the seasol and foliar applying but hasn't really helped yet. I will order some proper Iron supplement today.

If I am not mistaken.... Seasol is just a Seaweed extract. There is not iron in it unless you get the one that says it has iron added. Seas weed extract is a potassium and micronutrient source.

If you were just foliar feeding seasol you didn't foliar feed iron. Maybe why you have seen a change.

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