Backyard Aquaponics
A place to discuss aquaponics

Torsten, do you have a woodheater? if so, is it a wetback version?

I don't think there would be enough strong sun in winter to use a Trombe wall idea for greenhouse heating and therefore your water.

Although if you go to the Botanical gardens in Hobart one weekend; there are some holes top and bottom in the main pillars of the main wall. They used to build fires in them and the heat would soak through the stone walls, allowing them to grow citrus trees aspalliered along them. Not done any longer ofcourse. Some hot water from your wetback piped through the greenhouse or perhapse the water tank would do the same thing???

Ofcourse, if you get it working.... I'll be over next July with the beer and deck chair!

all that frozen water make me feel chippers

Trombe walls are a terrible idea. We can talk about good solar design later (I'm about to head off to the US for a week).

Evacuated tube solar collectors are getting very cheap ($2 US a tube now!), so if you can work out a cheap header design you should be able to build a very effective system! Even on Mt Ossa you should have no trouble keeping things warm given the right care in design and manufacture.

Alternatively you might consider using swimming pool heating tubes, or black painted copper pipe, or corrugated trickle collector, or...

But forget trombe walls, please?

$2.00 a tube? Who's selling em at that price NJH?
Lovely snow pictures D.

Hi All

I'm in Launceston. Having looked around on the internet a bit I have found some references to other species being allowed into Tassie. The University of Tas just recently bought in some Barramundi for a project. However, any importation of non-native species must go thru the head vet in Tas - haven't bothered to locate him/her yet. I suspect that one would have to demonstrate that there is no way that anything from one’s system can get into the local waterways.

I am interested in (at a later date) seeing if permission would be granted to allow the raising of large freshwater crayfish in the Aquaponics system. The giant cray is an endangered species but there is a large west coast cray that is not and it may be a possibility to raise them. Nothing is surer that if such beasts can be raised in a sustainable (or commercial) way that it would protect the crays from extinction.

That's what a friend claims he gets them for in the USA. I paid $33 a tube in melbourne. email me and I'll link you with my friend.

If you can make a trip to Launceston you can pick up bath tubs to use as grow beds for $20 a piece. They also sell timber and all sorts of other stuff that has been recycled

Hi Natoyarose

I have heard of the endangered Tasmanian Cray (Astacopsis gouldi) but what is this other cray you have metioned?? Im interested because to my knowledge there is no one farming any freshwater crayfish in Tas and all mainland species are prohibited over there.

I dont think you would fit too many of those giant freshwater lobsters in a tank would you?? Given that they can grow to 6kg!!!

Hi Mutley

There are 2 other species of giant crays – they don’t grow as big as Astacopsis gouldi

Astacopsis tricornis which lives on the west coast of Tassie. Females can grow to 1kg. They only breed every second year though and only have 100 eggs. This breeding cycle seems typical to Tassie freshwater crays with Astacopsis gouldi females maturing after about 14 years, and males smaller and younger at about 7 to 9 years. The females breed every two years with mating and spawning occurring in autumn.

Here’s a link re: Astacopsis tricornis
http://www.environment.gov.au/cgi-bin/s ... l?id=81550


Astacopsis franklinii is found in eastern Tassie. It grows to 60 grams only. It is slow growing with adults reaching maturity at four years for males and six years for females, and they live for approximately 15 years. Females bear young only every second year, with mating and spawning occurring April to May.

Here’s a link on them
http://www.environment.gov.au/cgi-bin/s ... l?id=81549

I would assume they are all probably slow growing but, as in all things, I do wonder what would happen if it was given a slightly different environment.

Cherax destructor is a mainland yabbie that has found its way to Tassie. They are blamed for dam failures because of their burrowing.
Yet another link www.growfish.com.au/Grow/Files/fn082.pdf

cheers

I guess because they are all so slow growing that is why no aquaculture industry has developed with them. Over here in WA we farm the local Marron and Koonacs and also the introduced (from the eastern states)Yabbie. Marron usually reach saleable size in around 18 months though the fisheries dept through a selective breeding program have developed a strain that grows much faster and only takes 12 months to achieve market size. Supplies of these are currently limited so I havent been able to access any to date.

Thanks for the links, I will check them out soon.

Hi, I'm from Tas, live on the Tasman peninsula and about to set up an aquaponics system, using old bath tubs for fish and 20lt veggie oil drums cut down the centre for food growing. I have lots of these drums so if they rust out, I don't care. I am wondering about whether the rust will effect the system.
I'm waiting for the IFS about fish species to use and so far haven't go a reply. I also live by the sea and we get snow at least once a year.

Hi Stormbay,
Tasmania is so far out of my field of experience. Welcome to the forum, there'll be some answers about the rust from someone soon

Hi Stormbay, welcome.... long time since I did my trip down to Tassie, thread has brought back some memories.

These been considerable discussion on the board about iron deficiencies in AP systems, so in one sense maybe the slow rusting might not be a bad thing.

Question is, would the rust be in a soluble ferrous salt that could be absorbed by the plants and beneficial.

Conversely would it effect the fish.... my hunch is probably not to any great extent, as the process would be so slow that even if harmful, the period of time exposed to any small concentrations of the rust would be limited by the period of time your fish remained in the system before harvest and consumption....

Lets assume say, trout... fingerlings to plate ... 12 months maximum...
unless you're aiming to grow them out to 2kg and go fishing in your tank for them

we have a saying here stormy, usually comes up when no ones got a real definative answer.................

"Take one for the team"

i think i got a bit of rust in my system when it was in its first incarnation, i have NEVER had to add iron

as Fe2O3 is not water soluble it will end up getting trapped in the media along with the fish solids where it will do one of two things

1) bugger all

2) get bioconverted somehow and add precious iron to your system.

Just be aware that the water is pretty highly oxygenated most of the time so your "rust rate" will be phenominally quick i think.