The Walden Effect: Farming, simple living, permaculture, and invention.

Aquaponic fish dieoff

Aquaponic growbed

I'm ashamed to say that my fish started ailing right about the same time as Artemesia and my reaction was, "I can't deal with sick fish right now." Predictably, not dealing meant they all kicked the bucket, then rotted within the tank (I really didn't want to deal with them) and fed the plants for a while that way.

Now that the water's cleared back up, it's time to figure out what I did wrong and get back on track. I suspected the issue was pH since that was the one part of the water chemistry that was still swinging pretty widely before I introduced the fish. Sure enough, upon testing, I found the nitrogen had all been eaten up but the pH was a far-too-sweet 8.0.

Aquaponic celery

It's possible the high pH is just a remnant of the cycling process not quite being complete. In the past, I'd lowered pH with lemon juice, but Aquaponic Gardening suggests citric acid (the acid in lemon juice) is a bad choice since it kills the good bacteria in my grow bed.

This time, I just did a partial water change (15%) using rain-barrel water (pH 6.5), which brought the overall tank water down very slightly. Then I used two tablespoons of vinegar to bring me back to neutral (7.0) pH. Here's hoping the pH stays a bit steadier over the next few days so I'll feel comfortable adding back in fish....

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About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.

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The problem with adjusting the tank with acids such as vinegar or lemon juice or bases such as baking soda is that they are transient fixes and will result in more wild swings in the long run. You want longer term buffers that will decrease the likelyhood of swings. there are chemical buffers that claim to do this, but I prefer more organic solutions, crushed coral/sea shells to bring the pH up. A small mesh bag of peat moss or a piece of driftwood or oak leaves/indian almond leaves, to bring the pH down. Of course both of those work much slower so the result will likely take a week to fully show up and the acidifiers will brown the water. Brown water is very good for fish. There is even a chemical in indian almond leaves that appears to help treat mild finrot in fish.

Anyhow as long as you are adding straight acids or bases to pH your water you are not addressing the source of the pH problem and the pH will not be stable so your fish will be sick.

Comment by Rebecca Thu Feb 16 08:28:28 2017
I've kept an aquarium since I was a small boy. Measured now in probably way too many decades! Balancing the water pH is HARD to do. I agree with Rebecca. Adding acids is a short term fix. pH is a stubborn thing and will, like golf, ultimately frustrate the players by making something that seems simple be actually very complicated. OLD water is the key. It can take months to get everything balanced and 'right'. I would hold off on the fish for awhile. Get your plants happy, then they will make the fish happy. Chicken or egg? Well I don't know. But I do know the plants will tolerate much more 'tinkering' than the fish will. Ultimately, let your tank age and normalize by itself. Less is probably more.
Comment by Tim Inman Thu Feb 16 09:36:42 2017
What is your aquarium environment like? Are you relying solely on your top plants? If you don't already i would suggest creating a healthy aquarium environment that produces enough extra waste to support your terrestrial plants. Otherwise you're looking at a consistently tenuous relationship. Black flourite sand is a wonderful in-aquarium substrate that is quite supportive of pretty much all freshwater plants.
Comment by Nicole Thu Feb 16 11:50:52 2017
Also, I recommend goldfish for your fish. They can handle a lot of conditions, and they are pretty. And best of all- dirt cheap.
Comment by Eric in Japan Thu Feb 16 19:29:53 2017
I found guppies surprisingly difficult to keep alive (given how much they're talked up online as an excellent beginner fish). Mollies were one of my favorite varieties since I found them to be much hardier. Perhaps a different fish variety will work better in your tank.
Comment by Rae Sat Feb 18 10:39:36 2017

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