Backyard Aquaponics
A place to discuss aquaponics

Sejin's water test results...

pH 7.8
Ammonia 0
Nitrite 0
Nitrate 7.5

Does anyone know if there are minimum levels of nitrate required for floating raft deep water growth?

I know lots of people run systems that always register zero nitrates, but wondered if a raft system made less nutrient available or something.

Thanks, BWII, Craig, for coming down to my place to take a look at my pond, and have water tested.
I better get the test kit soon.

For the moment, my mind is in too many issues.
Here is a list:

1) how to get right size grow beds in Adelaide,
2) which combination of system to adopt: constant flow, flood and drain with stand pipe or auto siphone. Paralle l or series for multiple system? Need to think of both effectiveness as well as cost,
3) whether to use the existing pump (8500 L) for a combination of multiple system,
4) plumbing: pipe choice and size and other parts,
5) straberry tower: how and where, in what connection to other system,
6) nutrient flow system under poli roof, need to find out whether there is enough light,
7) duck weed tray: find out why not growing fast enough,
vegie in floating raft: why not growing
9) vegie in unconnected grow trays, why not growing well when fish water is supplied
10) should i get more fishes? My pond is 5000 L.

I am sure there are more questions.

I forgot to mention the slime in your duckweed tank. This indicates the water needs more air I think. I have a small air pump you can borrow until you get a more permanent solution.

Do the goldfish eat duckweed?

Or less sun perhaps.
Is the DW yellowing at all?
If it is you might try putting shade cloth over it, to stop the yellowing and reduce the slime.
I have just done exactly that with mine, which had the same symptom(s)

Yeah it was yellowing, and the slime was enough to grow one of those big bubbles that slime does.

Oh, I am learn about duckweed.

I heard that duckweek does not like moving water, so i put it in a shallow container lid under sun.
It evaporated too quickly, so i moved to a deeper container and still left in a sunny spot.
Then, duckweed began to form thick slime.

Following advices, i now added more water and put in a less sunny place with shade cloth on.
I may change water once in a while although it is easier to add water than change it.
I found it strange that some people had duckweed tray linked to a circulating systaem when it was said it needs calm water. I am do. I am still not clear about this point.
But i see that even duckweed needs nutrients.

I have read someone advising others not to put duckweek tray as the first unit of a circulating system because it may take away too much nutrients from water that grow beds would need.

It happens that position wise, if I connected duckweed tray ian a circulating system, positionwise, it would be the first place fish tank water wil arrive. It is not easy to make it the last place before fish tank because it is in the highest position.
see my conceptual diagram 2.

Humm.

Oh, I am learn about duckweed.

I heard that duckweek does not like moving water, so i put it in a shallow container lid under sun.
It evaporated too quickly, so i moved to a deeper container and still left in a sunny spot.
Then, duckweed began to form thick slime.

Following advices, i now added more water and put in a less sunny place with shade cloth on.
I may change water once in a while although it is easier to add water than change it.
I found it strange that some people had duckweed tray linked to a circulating systaem when it was said it needs calm water. I am do. I am still not clear about this point.
But i see that even duckweed needs nutrients.

I have read someone advising others not to put duckweek tray as the first unit of a circulating system because it may take away too much nutrients from water that grow beds would need.

It happens that position wise, if I connected duckweed tray ian a circulating system, positionwise, it would be the first place fish tank water wil arrive. It is not easy to make it the last place before fish tank because it is in the highest position.
see my conceptual diagram 2.

Humm.

it's very easy to just pull a small trickle of water from your main flow by adding a "T" junction and a tap. This way you can add a trickle of water to your duckweed tank and have a calm flow, rather than no flow.

In my system, I put a tap everywhere that I might need one. It means I can isolate a part of the system if I want, or change it, or adjust the flow.

So in your system, make only 1% of your water go to the duckweed tank.

Duckweed does need flow, but it needs to be gentle. Duckweed would grow perfectly in your main fish tank, because even though you have good flow, the duckweed would still be able to sit on the top, and it would collect in calm places around your plants etc. But the fish would eat it all within a few days if you did that

Found a discussion on wooden growbed.

Making growbeds and fish pond with wood?
viewtopic.php?f=1&t=1474&hilit=Grow+bed+paint&start=30

Sejin's question: viable in terms of holding water and safety in handling edible things?
I register this existence of this discussion before reading it full.

An example.

Live Beyond's Mark II
viewtopic.php?t=760&start=0
Two 1800mm x 800 x 300 (5'9" x 2'6" x 1') deep with a capacity of 0.367 M3. Two more growbeds will be added later..The growbeds are made out of wood and lined with 25mm (1 inch) of foam for insulation and 0.75 EPDM pond liner. The liner is fixed to the side of the bed with a plastic strip.

I used green tongue floor boards 800mm wide, cut in half....screwed and glued to side of 90x45 structural pine frame...Painted with two coats of pink primer undercoat and two coats of enamel.
----------

http://www.pondarmor.com/
Seems like a reasonable paint option to replace liner.

Sejin

Make sure you get a quote on the wood. I think it might work out more expensive than that now, although sometimes I see floor boards put out on the street for rubbish, wood has become really expensive.

Another paint you can use is gripset51. It's a flexible rubber paint that's food grade and fish safe (according to the label)

I seem to remember being able to see tiles on your fish tank floor. Is there a liner, or is it tiles or something?

Another discussion on paint in 2008.

Dave Donley
Post subject: Non-toxic, food- and fish-safe finish or coating for wood?
Posted: Thu Feb 28, 2008
viewtopic.php?f=8&t=2984
Wattyl Estapol 7008 , 20L ( 10L part a + b ) for about 70 bucks , to do 2 kitchen benches , food safe

I put the white tiles that were left over from my house construction to make fish more visible.
Black liners had made fishes not very visible.