Aquaponics - Overfeeding

When I was even more of a kid, my favorite book was about overfeeding fish. It looked like fun.

Uneaten fish food (not poop)

One of the problems with overfeeding isn't that your fish sit in your bath tub and get uncomfortably large and interesting, but rather that the uneaten food sits in the corner going rancid.

A mature system can handle a certain amount of excess food as it breaks down into plant food via the normal nitrogen cycle. My grow bed media is kind of mature, but my water is almost all new from a few days ago when I moved the system.

Most of the nitrifying beasties live in the gravel, but I think there are some living in the water, the slime layer on the sides of the fish tank, and on things like my pump, and pump inlet screen etc. This can mean that, after an upset like a washout and water change, the system might not be quite as capable of turning ammonia into nitrates. I think.

fish so well hidden you cant really see anything

When I changed the water and location of the fish tank there was some inevitable stressing of the fish. Shown here is an image depicting not really being able to quite see the fish because they are still hiding.

As a result of the upheaval, they went off their food.

I think the amount of ammonia introduced into the system by feeding should be similar regardless of the fish eating it or it rotting in the corner, but because I had the option of removing the uneaten food, I removed it.

why do chickens have to stand on whatever you are taking a photo of?

A few days ago I finally tracked down a product I remembered seeing in the shed when I was a kid. It's a siphon for fuel etc, but it has a squishy hand pump so you don't need to drink so much petrol. I thought it would be perfect to vacuum up any uneaten food.

It wasn't.

It didn't work very well at all. That might be why nobody sells them any more.

Aquaponics - Success

Success! I've actually managed to out-smart my fish. This last thwarter was made from a plastic mesh designed to keep leaves out of your gutters.

It's a good thing I'm learning on my small blue barrel system. I'd hate to be making all these adjustments on, and drilling holes in, my big system.

I just spent an hour trying to get my auto siphon to work again.

In order to prevent my fish tank from getting too cold overnight, I tried turning off the pump during the hours of darkness (I now have a small air pump for oxygenation). The downside to this was an increase in ammonia and nitrite levels.

- The nitrates values are divided by 100 so they fit on the graph. (I'm told nitrates can safely be over a thousand, so nitrates are not a concern)

I think my nitrite and ammonia levels are still within safe limits, and it was only for one night, but I've decided to go back to running the pump overnight.

Aquaponics - Water testing

Its extremely important to make sure your water quality is within a desirable range. Aquaponics is remarkably stable and robust, but, for the first few weeks of setting up a new system it can require a little extra care. The best way to avoid any problems is to test your water every day until your system is mature and in balance or "cycled". (pictured here taking 30 days or so)

An aquaponics system is said to be cycled when it can process approximately 1 ppm of ammonia into nitrites and then process those nitrites into nitrates within 24 hours.

A decent freshwater test kit will enable you to get accurate test results for pH, ammonia, nitrites, and nitrates. It will set you back around 50 Australian dollars. They are widely available online or any good aquarium shop should sell them.

If you try aquaponics without water testing you will lose fish unless you are very lucky.

Add ammonia until you see a reading of 2ppm, then wait until your tests show ammonia is 0. Then add more and continue until your system can process 1ppm of ammonia and nitrites in 24 hours. Once you see readings of 0 ammonia and 0 nitrites you are cycled and can add fish.

Plants can be added on the day you first build your system but there wont be much for them to live on for a few days. My house water supply is rainwater and has some nitrates in it from normal environmental nutrient. Even normal tap water will have some nitrates in it so there will actually be something for small seedlings to live on.

Be careful to wash the soil from any store bought seedlings you transplant as they may have any number of additives that may be toxic to an aquaponics system. Growing directly in the grow beds from seeds is safest (and often quicker!)

Conduct water testing every day until you are cycled and then test every week or so or if ever anything strange occurs. Plants yellowing or dying can be a sign of something being wrong with your water chemistry and you might need to intervene in the early stages of your aquaponics system setup. More on correcting water problems later.

Always keep a record of your tests so that you can see emerging trends before they become an issue.