Backyard Aquaponics
A place to discuss aquaponics

The fish look great with the light.

Do the silver perch eat rice?

Nah... that's Asian Perch you're thinking of Bull...

I hear Pat the drum man has IBC's for 30$ that carried PVA glue. Ii's difficult to get out, but once the containers are cut, you can do it with a high pressure cleaner (I have one you can use).

That is cheap. I have to think about future grow beds on high shelves.
But i have to think about shape and look.
My son, more than my wife, tells me i am making our garden ugly.
Humm.

Sejin

I feel yr pain, Sejin, but really what could be more beautiful than a fully functioning AP setup???

Then again, beauty, as they say, is in the eye of the beholder, and quite a lot of the time aesthetic preferences are shaped by cultural norms.

I guess the space yr working with is shared, so yr gonna have to work together. Given that yr original idea was to create a healing garden, perhaps some climbers (beans/grapes/other vines) on yr stands could help mask the metal. Or Ginger. That's a great healing plant and can grow quite tall.

Just some ideas...

It has been one week since my system has been set up.
Here is a report on what happenned.
First, plant growth.
No remarkable growth on the grow bed where I planted commertial seedlings.

On the other hand, some of the seeds that I sparyed in the second grow bed sprouted.
In particular, the lettuce seeds that I sprayed in excessive number have come up nicely.

A so-so result on plant growth for the first week.

Sejin

So did you end up doing timed flood and drain? And if so, 15 mins on 45 mins off?

You could plant some seeds in dirt for you own comparison with the same light etc.

The second major event was fish death.
So far, four silver perches died, at a rate of one a day over last three days. Three were found dead floating, one each morning, and one was found at the bottom of pond this morning.
Initially, it was one of the smallest, barely over 2cm. Next one was slightly larger.
.
I would expect smaller ones to be less strong. But the third one was big (by my standard) more than 5cm long. The one found dead at the bottom of pond was also a large size.

This made me worry about the whole of silver perch group.
Gold fishes seem to be doing fine.

I have been doing water test everyday, and there was no visible change in the readings.
I added some tap water, an equivalent of 15% of total water since there has been loss of water in circulating water through grow beds. I find that there is more evaporation by ciculating water to grow beds.

---

Some reflection on fish death:

By the time the third fish died, I began to think in terms of percentage.
Perhaps, 10% death rate is not so bad.
That lead me thinking, "perhaps, (human) generals think this way, '10% casualty is not so bad."

In modern Chinese history, one finds a series of events where more than ten miliion people died. Around the end of the 19th century, it was peasant rebellions against modern Western armies. But the dealth of this scale happened even after the communist (largely peasant) revolution took over China in 1949(?). Apparently, the leaders thought that a couple of million death is inevitable in nation building, and not too bad for a long term success of nation. It is less then one percent of population.

I pass no judgement on such thinking and decisions, but it does make me think about human history.

----

Back to aquaponics.
I am amazed to see how quickly my attitude toward fish death changed from being emotional to 10% casualty is OK.

Sejin

But you soon run out of citizens/silver perch if you lose 10% every time you add water.

Whilst some losses may be inevitable, it's always worth trying to figure out where the losses came from.

I really think you should consider using your rainwater for top ups. Having to add 15% was no doubt unusual, but unless you add Adelaide water in very small doses, it will kill fish. The pH is still around pH 8.4 two or three days after I get it out of the tap. Straight from the tap its 7.4-7.6.

There is very high doses of chlorine going into our tap water at the moment.

Another possible cause for you fish deaths could be whatever sprays and additives were on the seedlings.

You probably did wash them, but just in case you hadn't thought of it, it's always a good idea to rinse new seedlings really well. Everything and anything could have been sprayed on them.

I have not been very successful in growing duckweed.
After a series of unsuccessful attempts in changing position of a tray with duckweed, from a strong sunny position to a mild sunny one, BW told me some movement and air supply would be necessary for an adequate growth environment. Eventually, together with other smaller grow trays, the duckweed tray would be hooked up to the circulating water of the total system.
Meanwhile, I had an isolated duckweed tray operating with a very small aerator that BW had lent me. This seemed to keep the water less stagnating, and the result is definitely better than before, but still not satisfactory compared to that of uncontrollable growth that one hears about duckweed growth. Another concern was that I should probably return the airator that I borrowed from BW since he might need it. I did not want to buy a new airator since I may not need it.

In reality, I had bought a big airator with 8 air outlets. I had tried it and found it is too strong and I did not need 8 outlets. It is true that I think of future expansion whenever I buy anything. But the air pump was too powerful and transformed the tranquile pond into a big spa. I ended up closelooping several outlets keeping only four outlets. And I turn the air pump on only occasionally when day is hot. After fish death, I decided to turn it on more often.

It occured to me today that I can use one of the air outlets for duckweed tray.
But what to do about the strength of air output?

Duckweed tray only need a small and constant disturbance. One idea was to put the air stone inside a bottle and place the buttle inside the duckweed tray.
The water disturbance was still more strong than was needed, but much better than before.
I shall see how it goes for a week.

What about making an air lift to bring water up from your fish tank. That way the force isn't too strong for your duckweed, but it gets the ammonia it depends on to grow.

Duckweed doesn't eat nitrates like other plants. It eats ammonia which it needs to get directly from the fish before the grow beds and the nitrifying bacteria have had a chance to convert it.

not sure if some one has said this before, But much to my horror SA tap water has about 1ppm of ammonia in it!

Tap water fill up was after fish death, so is not the cause.
I had only a small reserve of rainwater because I already used it before and my pond is big.
I also had filled tap water many times at 10% level over last 6 months. Each time, it was after fish death rather than before. My experience was OK.
Perhaps, the size of pond makes it a less sensitive issue.
Typically, a water test after tap water refill gave me no change in test result.

Sejin

I just tested for ammonia and get a zero reading.