Backyard Aquaponics
A place to discuss aquaponics

Hello, new here and would much appreciate some experienced growers feed bacl on a problem I have.

I planted these type of chinese choy greene leaf veg. Not bok choy but something similar but I dont know its name in english. In the first 10 days, it grew from 3 leaves to about 6 leaves very nice, then suddenly, all leaves started yellowing outside. I searched the internet and found it could be magnesium def.., so I added epsom salt. The first 6 days, new green leaves started sprouting out and I thought the problme was solved, when suddenly, all edges of the outer older leaves became dry white, and this moved towards the young leaves in the centre too.
i dont know how to attach a photo here.

To attach a photo

In the reply section go to "Full Editor"

You will probably have to resize your photos about 800 x 600

Tell us a bit more about your system

How big , how it is constructed ,flow rate , is it gravel based or deep water

Do you have a test kit for ph , ammonia , nitrite , nitrate ???

What are you feeding your fish

Terra's on the right track . Need some pictures of the leaves and the entire plant to really give you much insight. What part of the system did you add the magnesium to? Was it added to the system water or sprayed on the foliage? Sounds like this is a new system, can you provide more information, number of fish, grow beds, ammonia, nitrite and nitrate readings, things that would tell us nutrient levels and where they are coming from....?

So here are some photos.

I have a 4 month old system, with 3x 1000lt fish tank, all with about 20kg fish each. All connected with 1 grow bed, NFT and raft bed. More beds and nft will be connected in the coming days.

I feed the fish with a Tilapi grower they provide here in Mauritius. Not sure whats in there, but I guess some GM ingredients.

I tested water.
Amonia 0.25
Nitrite 0
Nitrate 5.0

I added a table spoon of salt in 1 fish tank on 4 occassion in intervals of 3 - 5 days.
Last month I also buffered the system with 1 TB calcium carbonate, potassium carbonate and magnesium epsom salt.
From 6.8pH back to 7.4 now.

I have no iron yet and will get that only as from May as its limited here.

My tomato have potassium deficiency signs but as the system is high in pH I cant add more.

Also, strangely, I planted bokchoy a week ago in the raft, and at the same time in the NFT. Those in nft grew from initial 3 leaves to 3cm higher and 5leaves, while in the raft, its almost no change from initial state when planted? Is my raft in trouble. I have 3 air stone in 1mt2 raft.

Awsome if you could help;-)

I attached photos and replied but somehow I dont see the photos although I re sized them to 800

OK, I messed up the size, here are the photos. The reply about the system is in another reply above

Hmm, well this is a tough one. I do think you have at least one deficiency but there are a couple of other possibilities - disease and chemical burn.

It looks like the leaf tissue became necrotic because the deficiency got too far along. I'd give another spray application of Epsom salts if you haven't already. Apply this early in the morning or not long before nightfall. Applications done during mid day and ones that are too concentrated can burn the leaves. Magnesium deficiency would cause stunting because it's used in energy transfer and lots of other processes.

Sorry to hear that iron is difficult to get locally. By raising your pH you might be causing pH lockout of iron. With your pH at 7.4 you probably need to add iron in the right form (EDDHA iron chelate is good if you want to add to the system water - if you have something else spray application avoids pH lockout issues). FWIW I like to be in the 6.0 to 6.8 range.

Can you get a better shot of the spots on the plant in the first photo. They look like some sort of leaf spot but I can't see them well enough and they could be normal for that variety.

-- Does the NFT come before, after or is it in parallel with the DWC? Just wondering if these are the last plants to get fed?

Could be bacterial leaf spot... https://www.google.com.au/search?q=bact ... 00&bih=770

+1 - Yep, that's what I was thinking but couldn't tell for sure.

Thanks for yor reply guys. Much appreciated. I was caught with work, sorry for delays in reverting back.

Seems like its amazing that out of so much in the field of Aquaponics, the disease issue falls on me in Mauritius!

Thanks a lot!

Hello, thanks for the link. Very interesting.
Would you guys have some recommendations for preventive measures in Aquaponics systems?

Mainly just try to prevent splashing of water up onto the leaves from any grow bed inlets. For most spray treatments you would like the water to have a chance to dry before nightfall. Bacteria need water for growth so if you can reduce the length of time that water stands on the leaves then you can reduce this kind of spotting. Once it's started you may be better off just pulling the infected leaves, depends on what is causing the spotting and what your conditions are. You can sometimes stop it by sprinkling cinnamon on the spots but might have to repeat if it gets washed off.



It's not just you, pretty much everyone will run into bacterial leaf spot at some point, especially during a stretch of rain. Except for the tropical sorts, I can grow pretty much anything, including snails, bacteria, mold and most insect pests here . It rains so much that grass grows in bare pea gravel for nine months of the year

Thanks a lot, I take good note of that!