Backyard Aquaponics
A place to discuss aquaponics

Hi all,
Here are a few pics of the grow bed I welded up to handle filtration of a 1000l IBC CHIFT PIST. It only has 300l cap. at the moment but I shall be making another one soon and perhaps experiment with some 100mm PVC improvised NTF strawberries.
I set it up and then went to Tassie on a course for 8 weeks and left it to cycle with nothing but Seasol and some fish emulsion in it. For some reason, my GF wouldn't pee in there for me but she did pop in a few seeds about 14 days ago. I have been adding ammonia special blend (pee) over the last 4 days and now have the following
NH4 0.5ppm
NO2 5ppm
NO3 100ppm.
This result may also have come from going from constant flood to 15/15 flood and drain, killing a few greeblies and adding their bits to the mix. The Nitrate level has encouraged me to sprinkle some more seeds in there (Radish, spring onion, spaghetti squash, and more Bok Choi). Once things stabilise, I would like to pop in a few Barra and some Redclaw. If I have been understanding you guys right, my current growbeds ( read: to be added to shortly ) can filter for 3kg 'fish'/100l medium, which makes me think I can start with 20 fingerlings and progressively start harvesting them at 500g to maintain about 9-10kg live weight in the IBC. If I am mistaken here, I would appreciate some feedback very much.
In the photos, the beds are raised by bricks. There is going to be a raised flower bed there and I didn't want corrosion to be a problem in the future- just in case you were wondering...

I have to say thanks for the site because up till now I have just been reading with interest everyones posts and it has taught me LOTS. Now I am looking forward to contributing while I go through my "L" plates. Also, I am in Cairns and would be very interested to hook up with anyone else that has the bug. I can weld OK so if I can help with any ideas you have we may be able to work out some arrangement.

Thanks again.

Nice looking setup, look forward to watching how it goes for you. I am in Darwin and just starting out as well, so we should experince the same sort of trials and tribulations sharing roughly the same climate.

The 3kg per 100l guideline is one that I would recommend NOT to follow as it would be similar to riding a dirt bike at the edge of a cliff. We tend to recommend 20-25 fishes per 500l of filtration and I would certainly consider halving this amount for a new system that is less than 6 mths old.

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ivansng, when you say 20-25 fish, at what sort of weight are you thinking and what type of fish?

It's immaterial.... that's the maximum load for the filtration capacity...

Your nitrification will increase as the fish growth and feed rates increase... but that's the maximum level...

There's suggestions sometimes made that you can 2x fish... because they're small... with the assumption that you will progressivly eat them at around 3-400gm...

Most people don't... and usually have not only twice the fish load they should have... but half the filtration...

And franticly metabolising, rapdily growing fingerlings.. fed at higher protein percentage feed... and/or daily percentage rates and frequencies....

Will produce as much wastes as 1x more mature fish... despite their size...

Ok so instead of 20 fingerlings I will just have 10-12 while I only have the 300l of filtration and then once the next 300l GB is on line then consider 20 fingerlings. Does anyone have any thoughts as to how many fish a redclaw represents then? 1:1?
Also, any leads on a good source of Barramundi fingerlings in the Cairns region and also maybe Jades for the winter?

I wouldn't worry too much about the Barra not being harvested though...

Well yes except that when you add the new growbed, you need to remember to allow time for it to cycle up and not just continue feeding 20 fingerlings without monitoring ammonia and nitrite levels.

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Oh yes, I hope you are not considering mixing species in the same tank especially of different sizes.

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Ammonia load is directly related to waste production, waste production is directly related to feed quantity.

So in regards to how many fish a redclaw represents-- well, it depends how much you feed them

The plan is to get the 10 fingerlings and grow them out to harvest. My take on barramundi is they will eat anything that fits in their mouth so I will be careful not to put in anything else while they are in there. The other grow bed will have to cycle up anyway so I won't be adding anything further till I harvest the fish. My aquaculture friends here say that Barra will get sluggish and even get susceptible to white spot in the winter temps of Cairns, so I hope to switch to perch around june, july- relying on peeponics perhaps to avoid a nutrient slump. It sure has worked well during this no fish period. The tomato plants have doubled their size in 4 days!
Thanks for the feedback so far.