Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

I have been a stalker on several forums for some time now. I have just not taken the time to do a full write up of my story. I hate to say it but I am now setting out my story in the hope that I get some ideas to solve some of the problems I have encountered. I live in a small town, Homer, in Alaska and have been very involved in my community as a nurse midwife. I live in a community with a strong desire to have fresh, organic produce. We have the highest number of high tunnels of any zip code in the US. We have a fabulous Farmers Market in the summer. I have been saying for years that we really need to be able to provide local, fresh greens to the community but no one had done that. I was playing around with hydroponic growing in the house. I successfully grew lettuce, basil and tomatoes to eat each year. A few years ago, a friend gave me Sylvia Bernstein's book to read. I got really excited because I really felt that aquaponics could solve some of the problems that I would have with hydroponics. So I began to do a lot of research and we went to visit some farms that were already running. So Alaska Aquaponics was born. We built a 22 x 36 foot green house with an insulated foundation and triple wall polycarbinate. I have done a lot of research about running the greenhouse, fish, plants and marketing. I feel like this small greenhouse will hopefully be a prototype for a larger system if it all works as planned. At the very least right now I can provide greens to the local health food store and have a small CSA and we get to eat REALLY well.
The system
I started with a 1000 gallon tank for a fish tank, I usually keep about 800 gallons in it. It is tall so to make the smallest foot print possible. Water runs through a SLO by gravity to 3 4x8 foot grow beds with hydrocorn. My fabulous bell siphons fire about 4 times an hour. The water then flows by gravity to a 8x24 foot raft bed. The one pump in the system sends the water back to the tank with continuous flow. I grow produce that I can cut and come again in the grow beds and the rafts hold lettuce, bak choi, mustard greens and other greens. I must say - it is all very beautiful and brilliant! I am very proud of how well it works. I have room to try some of Nate's towers and Vlad's dual rooting ideas and maybe some small wicking beds. I love to experiment and tinker. I set up aerators for the raft bed and for the fish tank. I just got some LED lights to try out for this winter. I heat with natural gas and am set up to do a climate battery. I also have hot water pipes run through the floor so we will set that up eventually too.
I started with some goldfish that I already had and in early March we added a couple hundred small Koi. I had cycled the system and had Nitrates all through February but once the plants really started to grow I never saw Nitrates again (or ammonia). I decided I needed some more Koi once I started running the rafts. So I added another 125 from the same source.

I had some great months with happy fish and plants but the end of June I started to get a dead fish every few days. They were unmarked and looked fine. Some were bigger and some were smaller. My water tested fine. My Ph was consistently 7.8 though I expected it would go down.
Water temperature would hover right at 65 degrees. I soon realized that these were not just random deaths. I was getting 1 a day and by mid July, several a day. Still not marked. They were flashing (jumping) some and sick ones were resting on the bottom of the tank. I tried just taking those out and I tried salting the whole system (several times). I actually looked at them under a microscope to try to identify the culprit but saw nothing. In August they began showing what I think was a secondary bacterial or fungal infection with lesions and fin rot. During this time my pH actually did drop to almost 6 and I did buffer it up thinking the fish might be less stressed if it was higher so I used oyster shells to do that. Meanwhile, I have lost a lot of fish and was not feeding since they were not eating well and eating can stress sick fish. So now my plants start to suffer from lack of nutrient. I have added some worm tea and maxicrop to try to help them. My worms in my grow beds seem really healthy and seem to be multiplying.

I removed my fish from the system entirely and treated the with many different treatments. Tetracycline, more salt, Melafix (teatree) and finally malachite green and formalin (ugh). They just continue to be sick. I set them up with their own grow bed (for filtration) and keep them completely separated. I thought it was just them so I gave it a few days and put feeder goldfish in the system. Now, I know they are not the strongest or healthiest but after 3 weeks in there - they have started to die too. No sign of any of the lesions - they look fine but I pulled 10 dead out today. I am sending some fish off to the State Lab tomorrow to see if they can help me figure out what is wrong.

So I am looking for any other ideas, what could be causing this? What can I do to stop it (even if I don't know what causes it)? If I need to take fish out of my system, how long and what can I use for nutrient that would allow my to go back to fish eventually? I sell some produce so I don't think peeponics will work. I am still really excited about this project but could sure use thoughts or advise for this problem.

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Hi, Sonja. I have experienced the same cycle with my fish the last couple months. I've gotten some advice from the aquaponic specialist from University of Ar. She recommended water changes and to not feed them. If you change water, she recommends 20%. She also recommended a product called Zeolite which filters out ammonia, heavy metals and other things that are detrimental to the fish. In my case, my new fish were too small and she said couldn't handle the nutrient load. I planted all my beds, did several water changes, quit feeding for a week, and tested the water several times a day to monitor and make smaller adjustments, keeping PH within .4 max variance.( this is very hard here because my water is 8.4 from the tap and I kept it at 7.4 thru this) I also purchased the zeolite in filter bags and attached it to the discharge tube into my sump tank, causing all water to run through it. I haven'tlost any fish the last 2 days and started feeding 3 days ago. I'm hopeful it's over for now. I sure hope so since I've lost about 425 fish in the last month. I know exactly how puzzled you are about this, and hope that this info may help you.

Hi Sonja, sorry to hear about your troubles.

@Cindi, in your scenario i.e fish not being able to handle the nutrient load, zeolite to sequester ammonia, and water changes was pretty good advice. Unfortunately, Sonja is having 'the opposite' set of circumstances. No showing of nitrates, no ammonia. So we'll have to help her figure something different out, that fits her scenario...or at least try to...

Flashing is just a sign that something is irritating them, hopefully the state lab can perhaps shed some light on the matter, You've probably already thought about 'the usual culprits'...galvanized metal...copper in contact with the water...leaky stray electrical voltage from a pump/equipment...etc...

As to running your system without fish, and not using humonia since you are selling produce, while not relying on typical hydroponic nutrients...sure, there are a number of ways to do that...safely so that you can one day plug your fish back in. 

You'll need inputs that make economic sense and that you readily have access to.

Physiologically speaking, how plants grow is how plants grow. Weather soil, hydroponically, aquaponically, vemiponically, peeponically, worm-tea ponically or "what-ever-pre-fix-ponic" we come up with. Plants are not very picky as to how they get their ions

To keep your bio-filter going you will need an ammonia source to feed them with. This can come from many sources. The dead rotting carcasses of your dying fish would be one potential source. (Free, available ready for nutrient recycling).

If you have farm animals, making your own salt petre from their nitre beds would also be viable, though it may be more viable to purchase the salt petre, as this process takes a long time. Salt petre would give you nitrate, calcium and potassium. Salt petre does not rely on bacterial action to free up those elements and make them plant bio-available.

Sea water is a great source of magnesium, some potassium, and many trace elements.

If the 'yuck factor' of rotting fish is too can purchase a manufactured and pre-packaged fish emulsion product like "Charlie Carp". Many Aussies use it in their winter to run systems fishlessly, growing veggies, until it warms up, and they re-stock the system with fish.

If you have a worm farm, hanging paint strainer bags of castings near an air stone works, but you will still need an ammonia source to keep you bacteria alive during this time.

Just think about the 13 plant essential elements that plants need to grow (and having some N in the form of NH/4 to keep your bacteria alive) and you'll be fine.

Linked is a page with some common substances and their NPK and other mineral values. Some may not be appropriate unless processed correctly (mammalian feces...rabbit droppings etc)...Most have, or would work just fine. Just don't "over do" it. Keep things somewhat balanced.

You can also run your system on fish food (provided you are using a good quality well formulated feed) without the fish. Worms and microbes with do the same job as the fish, only leaving more of those essential elements for your plants, since there would be no fish to sequester the nutrients (turning the food into fish muscle tissue and fish bio-mass) contained in the fish food

Hope some of this helps at least on the plant and bacteria side, and possible ways to run your system without fish. As to the mysterious fish deaths, there are too many variables for any of us to reliably diagnose from way out here in internet-land.

I hope that you and/or the lab can find the root cause of their deaths.

The update from today from the lab is that the autopsy does not show an obvious cause of death. Lots of external bacteria but not anything unusual inside. They are going to grow some samples out. The Dr is thinking some kind of viral infection with secondary bacterial infection. May take a while to find out. Meanwhile I have a pretty steep learning curve to figure out what I should do to keep my system going. Vlad, your advise is super helpful and I have read through the link you recommended. Need to see what is available here. I am daunted by figuring out amounts and what to use but shoot, I've gotten this far!
@ Cindy, it is really kind of you to share your story, it made me feel better to know I am not alone. I expected I might kill fish by making a stupid mistake that I could fix but was not prepared to not know. Hope your fish are still recovering. I will keep you updated.


Did you get to find out what the problem was? I am keen to understand what happened.

Zero TAN & dead fish?

My wife is a nurse educator & midwife & I am an air force electronics/ medical (CT,MRI,Nuclear Med & Pathology) engineer. I am searching the blogs for stories such as yours so I can incorporate outcomes into my AP operations reference manual plus ensure that our AP Lab can measure or deal with such a problem.

I run 4x 1000L IBC, 2 inch SLO’s , then Swirl filters then a mineral/ bio filters of ceramic beads, Zeolite & spaghetti mats to 4x 600L sumps then a 12K Litre/hr sump pump.

I use Humic Acid, EM & Probiotics in the system to help keep the bacteria balance on the good side.

The scientists here in Thailand say that the biggest problems are Bacterial infections & low DO due to water temp of 26-28c. I am doing everything possible to get the Bio filtration working well so I can run a 10M Deep Water Raft as well as grow beds. There is Zeolite in all grow beds.

There are Red Claw & Giant Malaysian Prawns in the 4 interconnected sumps plus a few Tilapias that got sucked up the SLO in sump pump.

I run a 1% sea salt solution (100L hospital tank)on all new fish which are Tilapia, Barramundi, 7 Stripe Barb, Julian’s Golden Carp, Spotted Featherback  & Snakehead fish. The system has been operational 6 months.

I use a seaweed extract from Finland with German Humic acid & 17 trace elements on the grow beds weekly. I am pretty sure that this mixture will keep your grow beds going & if you need more NPK, there are several Organic supply places on the net.

Look forward to your future posts & resolution.


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