Backyard Aquaponics
A place to discuss aquaponics

Sounds great Hew. Can't wait to see the pics.

Looks like Hew is a bit busy - probably trying to keep those barra warm

Would certainly be a challenge - the same one I'm having here in SE Qld.

hello all i'm having trouble feeding the barra let alone the other daily duties as i have a broken ankle and two fingers, done whilst cleaning my indoor aquarium thanks to my dog that got in my way and i went arse over heels on the floorboards.

scott i will pm u regarding ur get together i'm already booked but i'm working on that.

temps, water temp 26-27 with 450w heater per tank and air temp 32-33 heated via split system (2.8A on heating) and also homemade solar heat exchanger that works when its not winter (2-3months i cant use)
In 2500lt water we grow out fish to plate size and hope to get 200kg with 450 fish starting at 80mm in approx under 6mths

Good luck - thats a lot of power though, is it economical?

200kg of biomass in 2500ltr of tank ==> 8kg of fish/100ltr (approx - plate size) ...

That's a pretty high stocking rate for an AP system Hew.... normally in AP we wouldn't stock much above 3kg/100ltr (75kg/2500L).....

6kg/100ltr (150kg/2500L) is possibly acheivable in a mature, constantly monitored system with a high degree of experience....

What sort of aeration system are you using ... pure O2 injection?....and what sort of DO readings do you run at...?

Remember nearing harvest, you'll be feeding about 10kg of food a day....based on 5% biomass...

How many growbeds do/will you have.... frankly I don't think 1200 holes of NFT will cope with that much feed load... on their own anyway....

Unless you've got some really heavy duty external bio-filtration and solids removal systems....

Can you post some pictures of your "sand sump" and bio-filter??... really interested to see how you're trying to pull this one off...

Actually... from your reply, "we grow out.." it seems that you may have already been doing this for a while....

Even more interested Hew.... pictures please....

i was reading a very interesting review of south australian aquaculture farms the other day. Among other things, one of the question series was how heavily do you stock your tanks and what form of filtration, solids removal and oxygen injection and chemical filtration do you use. It was shown that at anything above 5 kilos per 100 litres, (from memory) fish mortalities increased dramatically if there wasn't oxygen injection and/or ozone or uv treatment.. I now feel that anything above this without UV or ozone and o2 injection is really pushing your luck and risking the health of the fish. At a minimum, fine solids removal needs to be done, and they did quote a figure down to xxx microns. I think rupe that the figures are proposed and like everyone else here, it will be a learning curve for Hew.

Agreed Monya... quoted the figures above for Hew's benefit, as they're the ones often touted about in relation to AP...

Recently, at the Recirculation Technologies course I attended at Natfish, I mentioned to Glen Searle (Snr Lecturer and highly regarded aquacultural researcher) that we stocked at a moderate level in AP systems @ 3kg/100ltr....

To my surprise he replied that level of stocking was actually quite high for recirc tank systems...

For instance.. compare to data from the silver bream trial in the research recirc tank at NatFish (12000ltr)... that I posted here...

viewtopic.php?p=140456#p140456

320 fish for a total bio-mass of 334kg.... Average weight 1.044kg ...

So, for comparison... 334kg/12000L.... is roughly a stocking rate of about 3kg/100L

And they have some massive... and very expensive.... filtration gear....

That's why I've asked Hew for details of his bio-filtration.... I also have doubts as to the chances of success at the stocking rate he suggests, particularly in small 2500ltr tanks...

But, would prefer to hold comment until Hew discusses his bio-filtration capacity...

I'm hoping that Hew hasn't been blinded by "quoted" high stocking rates from overseas "battery" tilapia systems... or by "inflated" figures/advice from "commercial interests" with a vested interest in pushing a product... usually pushed as a "turnkey" solution...

Aussieponic and myself bought out tanks from a guy who was running a small commercial aquaculture operation, growing jade perch. When I told him that we try to get to stocking densities around 6kg per 100 litres, he nearly laughed. He was running much, much higher stocking, though I don't know exactly what. The thing is though, this guy had a large ozone generator and all sorts of fitration equipment.

Even with large grow beds, filtration with that sort of fish load would be required - they just couldnt handle that amount of crap.

Hi Hew, sounds super interesting what you are striving to achieve and i wish you all the best of luck, and like everyone else I am hanging out for a heap of pics. Hopefully you wont get scared off before the pics are uploaded

primary mech. filter,
filters down to 125um 1/3drum style filter

secondary mech filter / primary biofilter,
clarifying bead filter, which is a high pressure inline biological and solids interceptor. Its capable of upto 480kg standingcrop biomass after its established and capable of 1%body weight feeds
90% void space and specific surface area of 1400sq./m in 1 cubic metre

the sump is 4000lts contains biofiltration, degasing filter and it also feeds the aquaponic grow chanel(primary supply for vegies) also contains 3000lts biomedia, leaveing 1000lts for storage water.

this is housed behind the shed using two 1/4 hp sweetwater pumps 1 for grow chanel system 1 to do the rest.

no o2
we use a big blower which we achive 87%DO 6 air blocks in each tank
we are looking into changing over o2 but it's not that simple when back systems are involved.

sorry I will be held up ATM due to my injury this took long enuf to type let alone my daily tasks to do on crouches, so bare with me on my pics as i cant reach my camera up in the cupboard

also fish have been running sweet on their own with this filtratrion system(wasnt cheap)
our grow tunnel has just been finished brand new so thats why our system is like it is,we allowed to add this tunnel since day dot but 1 thing is $

Kewl Hew... look forward to the pics when you're back on your feet...

Be interested in seeing the filtration system.....especially one with that sort of capability... can you post a link to the supplier... and/or details... and price??

How often do you monitor your water params at the moment... guess the barra are essentially fingerlings at the moment... but in six months, with that (potential) biomass... I'd be interested in what sort of monitoring procedures you have/intend to put in place...

Take it you have large amounts of water on standby if required...

It is my job atm, so i'm in the shed most of the day do allsorts so i have also got my little tv tuned to the olympics so i'm sitting out there lots lol its warm, comfy chair, watch fish, tv, ponder about and fiddle, but the tunnel will be held up as in planting out cos i'm overdoing it already on my leg.
still need to comission the growbed and plumb up the pump into the dedicated outlet off the sump/aquaponic supply

Sounds like you know what you are doing anyways