Backyard Aquaponics
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Probably has to do with temperature. Mine did the same thing this year in both soil and a DWC run. Pipe style systems heat up faster so that is likely part of it and we get low temps at night which can also contribute to this. Not sure what to tell you to fix this but maybe someone else has some ideas.

https://www.gardeningknowhow.com/edible/vegetables/bok-choy/preventing-bok-choy-bolt.htm

Yes that's the best I was able to find as well. I had to pull out the bolting choysum as it was useless trying to do anything with it at that point. A small amount of aphids started to find their way in one too. Some of my bokchoys are starting to elongate as well

Thanks for the link you shared. That's the best I was able to come up with as well.

Btw, any advice on stunted seedlings? I am experiencing with micro kratky seedling tray, another tray with coco coir and perlite, and another fruit container with soil.

The kratky seedlings seem to have stunted, so I added a little bit of Fe EDTA last night, and misted the coco coir and perlite seedlings with Seasol. They all have formed their first true set of leaves. Not enough sunlight perhaps?

Last question please : what techniques do you use to minimize transplant shock from seedling tray to AP? Do you think a foam collar around the seedling in a raft would be choking it? I have done some research on this and could only find articles on root growth compound (some use honey). Perhaps I'm transplanting too soon? My okra, cilantro and pepper seedlings have stayed the same even though everything else around it is booming.

Thanks for your input as always

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I'm thinking the water may not be warm enough in your Kratky system. Check the water temp. The minimum temp for good growth will vary depending on the plants (whether they are cool or warm growing plants). How are you supplying the nutrients for this?

Okra and pepper are both warm weather crops so if your temps are cool that may be why they haven't taken off. Basil is even more sensitive. Tomatoes are also a warm weather crop but they don't seem to be as sensitive.

I don't claim to have the seedling bit dialed in but I mainly start seeds either using the baggie method or in Jiffy pellets. Baggie method is for seedlings that go into the AP media beds and it's usually a direct transfer as long as the beds are not getting really hot (There's also another change for damping off - see later note). Jiffy pellets go into starter trays sized for them and are then transferred to 2" net pots in the DWC or directly into soil. You could probably use coco coir pellets instead of Jiffy pellets. I've found that these hold together well enough once the plant roots are established that having them disintegrate into the trough isn't really an issue for me. residual plant tops go to my chickens and the rest, including the pellet, goes into the compost pile. I don't know if Jiffy pellets would work for a regular DWC - my plants start out floating directly on the water but once they develop roots that are long enough I raised the styrofoam so that there is an air gap - I only have water flow aeration and no bubblers in the DWC unit.

Note: If you're having troubles with damping off in the media beds then grow the seedlings from the baggies to a larger size in some other media before transferring them into the media bed. You'll have to rinse the media off when you do it this way but at least this helps against damping off.

When it's summer I'll direct seed some things into the media beds (radishes work well this way).

One other thing I should mention is that I use wicking beds and AP. The wicking beds warm up faster in the Spring and do better in our climate at that time of year. The AP works well throughout the summer and into the fall. It also does a good job of keeping the growing are from freezing in this mild climate and that lets some plants over winter without having to throw a blanket over them.

Hey thanks again for the reply!

For my kratky seedling tray, I use AP water with a pinch of Fe.

I'm currently experimenting with different seed germination and seedling growth methods prior to transferring in AP system. That includes:

1. germinating into small pebbles and watering with AP water in hopes that it provides the least amount of root damage and transplant shock.

Result: good germination, easy to untangle roots

2. germinating on damp tissue paper in petridish. Have been adding cinnamon powder and damping tissue paper with hydrogen peroxide.

Result: good germination. Spores formation that kills the seedling sometimes. But difficult to untangle roots from each other and the tissue paper also

3. baggie method kept in coat pocket

Result: very poor germination rate. Perhaps not enough oxygen present when plastic adheres to damp paper towel? Are you following a method close to this video? https://youtu.be/dirz0WIMQi0

I currently have empty slots in my AP as seedling growth rates have been poor. Trying to build up to a smooth plant rotation program.

Some seedlings have taken a beating from slugs recently.


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Yes, this is basically the baggie method I use only I don't bother much with seeds that need cold and warm cycles. I use a dampened paper towel section (water, not Hydrogen peroxide) and I put the baggies in a shoe box and either out in the garage for cooler temps or on top of the fridge for warmer temps. I try to get the seeds very soon after they sprout and only use one layer of paper towel - It's easier to remove them before they get too entwined in the paper towel but you can always cut or tear the paper towel if you have to. I don't pot up like he does - once it sprouts it goes to the media beds but I provide some protection if needed (mainly a bit of shade to help them acclimate when it's hotter). This method lets you see which seeds are viable if you have an older packet of seeds and don't want to waste a lot of effort on potting up those that aren't. Never noticed poor viability but I'm growing for myself not commercial. I always start more than I need and am willing to throw a few out if I don't need them.

Using a petri dish sounds like a good method. I think anytime you germinate on paper towel you're going to have to untangle the mass unless you catch them early. If you get your petri dishes in plastic packs you could try repacking them in the original bag vs just stacked without the bag - I doubt it would make any difference but it might tell you if air is involved in causing the lack of germination. I've though about using a weak gelatin or agar media to get seedlings started and this would help (I think) with separating the plants. Orchid growers do this but they have to provide nutrients in the media because the seeds have none stored - you really just need a sprouting media, not something to grow plants further. I'd add whatever gets used while it's fairly hot to reduce contamination and keep the cover on while it cools. Once it sets add some seeds and cover it back up...

Thank you for your tips and advice. I will try the methods you just shared and I am confident I will have something that works

Lastly, may I ask your opinion on my protocol due to chlorosis (in NFT and some of raft crops) and a yellow tint on younger leaves showing up again? Basically older leaves show chlorosis, and younger leaves are shower yellow tint. My understanding is yellowing on younger leaves = Fe deficiency, chlorosis on mature leaves = Mg deficiency correct?

I am doing a foliar spray of 5g Mg, 1 cap Seasol, 1 tsp Fe EDTA mixed in 3.5L AP water 3 times/week. I am trying to find a gentle preventative measure bc I am hoping to sell some crops at the local market.

pH 6.4
NO3 40ppm
Outside temp. has been around low 20's day and night

Nitrification happens fast and pH falls every week in my system. Still have to get my hands dolomite or limestone as postage is on lockdown.

Beans, snap peas, kale, strawberries and basil are doing exceptionally well atm.

Keep well

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This is typically what I think when I see these symptoms. There can be other causes like root rot, viral infection, pests and diseases. I think your symptoms are from run of the mill nutrient deficiencies and not from other causes though. The plant shape and size looked good just not the chlorophyll content.

Are you actually using 5gm of Magnesium or is it actually 5 gms of epsom salts? I have a feeling that the true magnesium content isn't enough to get some of the plants over the hump. If it's epsom salts just up the amount to about twice what you're currently applying until the symptoms disappear. If I have this figured right the current dose is less than a quarter tablespoon each time. FWIW most systems rarely have to add magnesium and in most cases it's good to keep additions to a minimum.

No way...was that my issue all along? Yes, I was using epsom salt all this time thinking that it was a potent form of Mg? I bought it from the pharmacy and the box doesn't give any info on the actual Mg content. How much do you reckon I should use per Litre at the root level please?


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I can't say what you need at the root level. Most epsom salt containers will tell you how much to use per gallon for spray applications and that's the way I have used it (only had to use this a couple of times early on but there may be some benefit to regular dosing at lower amounts, not something I do but I think others may do this). Epsom salts is basically Magnesium Sulfate with 7 water molecules attached so there is a good amount of magnesium but water makes up a large portion of what you're adding. Try about 1 tablespoon of epsom salts per gallon of water as a spray (if the metric converter I used is correct that's around 25 gm and a us gallon is roughly 3.8L). Use this every couple of weeks until the symptoms disappear. It's important not to apply too much during warm weather since this can burn the leaves. It's also a good idea not to apply during the hottest part of the day. You may find you need monthly applications after the symptoms disappear or your system may get enough through other sources like mine does. Since AP systems are recirculating, I take a minimalist approach with additions to my AP system and only add if I have to.

If this doesn't help then you could increase the frequency of dosing to every week but if that doesn't help after awhile then something else may be going on.

I'm always amazed and grateful for the advice you share. Thanks so much for the numerous prompt replies you have sent me, and taken the time to type out. Surely, your knowledge comes from years of experience.

I am doing foliar spray to bring my crops up to speed. It's interesting to see how my media bed crops such as leek, celery, beans, strawberries, cucumber and sweet peas are taking off and lush green with some signs of early chlorosis on older cucumber leaves.

Raft bed and nft are the ones suffering but only on kangkong and slightly on my basil. Otherwise bokchoys, swiss chard, spinach look good to me. Some school of thoughts advocate for slow flow rate, and others 400L/hr per sq metre. Mine is a slow flow rate. I wonder if I should increase it?

My pH has stabilized at 6.6 and NO3 go down to 0ppm for the first time since October of last year. I am pleased about the pH, and surprised about the NO3. I reckon I need to up my feed rate correct?

I've researched some other articles which recommend the same epsom salt foliar spray dosage as you stated. I have learned to err on the side of caution thanks to you, but I think I need to up my epsom dosage a little.

Take care and thanks again



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I am also surprised by the crops in my 2nd system that I built during the confinement. It hasn't cycled yet.
pH 6.4, NO3 80ppm,NH3NH4 1ppm from biofilter media that I washed off in the new system plus 1 cap Seasol

I suppose the plants are growing bc it's getting a high dose of NO3 even though a slight yellowish tint is starting to appear.

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0 nitrate really just means it's being used as it's formed, not necessarily that there isn't enough. You can get good growth even with nitrates at zero. Usually if you don't have enough you start to see yellowing and often other nutrient deficiencies show up. If you want to up the levels and the fish are willing to eat more then sure, add another feeding or just increase it a bit - as long as your filtration is up to the task it should be alright. Adding another feeding spreads the need for biofiltration out a bit so you hopefully don't get a spike in ammonia or nitrite because you've asked too much of your filtration.

Not sure but I think the yellow color on the last photo might be normal for these but you probably have a better handle on what it's supposed to be than I do. A lot of times plants will lighten up if conditions are bright (it helps keep the leaves from getting too hot). Another cause is a nitrate deficiency. Doubt it's nitrate deficiency since your levels look good. The Kale plant that looks good in the same bed makes me think that it's the normal color.

Right, I read about systems having 0 Nitrates with plants going well. Never thought I'd have such a reading. I'll keep feeding normally as I dont think my filter will be able to take it. I cleaned my RFF today and it was doing a good, except that I noticed an anaerobic smell to it. I clean the RFF and biofilter every 3 weeks. Any ideas on how to prevent the propagation of anaerobic bacteria in an RFF pls?

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Anaerobic bacteria are relatively slow growing so the solution to the smell is to clean your RFF (Radial Flow Filter for those who don't know) more frequently. The anaerobic bacteria will still be present but won't be as much of an issue. You probably could manually do this once a week and be alright. Some people have setup a slow release of the solids to a mineralizer. Web4Deb has a video on YouTube about his setup and there are probably others if you look around. If you don't already have a mineralizer the breakdown of solids this way can give you nutrients to add back into your system.

If you're still getting odors bad enough to bother you then shorten the time between cleanings. I am fairly tolerant of the odors so I clean my RFF about the same as you are currently doing. The odors do represent the loss of nutrients as gasses so it's a bit of a waste

EDIT: Forgot to mention that the gasses released by the anaerobic process aren't good for the fish. Yet another reason to remove the solids more often. My RFF is not in continuous use (it's used to clean a pair of upflow filters) and the water doesn't flow back to the fish tank until it's been aerated for awhile to remove some of the toxic gasses so I don't really need to remove the solids as often to protect the fish.

Thank you! Will consider all your suggestions

My cousin has seen my little AP system and wants one of his own He has an existing pond. Do you have any recommendations for filtering when the FT doesnt give you much flow from gravity to the ST?

I was thinking of:

1. drilling a 2 inch hole to fit a SLO from the FT

2. Making the two lower cascade pond compartments into one ST by drilling another 2 in hole down at the bottom.

3. I was hoping of having some kind of in line filtering with the SLO before water flows to the ST(s)

Am I out of topic and should've made a new thread ? :/

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