Backyard Aquaponics
A place to discuss aquaponics

Interestingly niloc, their black bream came from WA. Couldn't source them from the east coast. 11 hours point to point and they never lost a fish.
I can ask next week where they got their cats from if u like.

Good night last night, covered some general industry figures and jumped into the start of water quality.

Some random bits:

Interestingly in Victoria, there are less than 200 licensed aquaculture setups. Trout/salmon accounts for 50% of sales at the farmgate. Native finfish, (the stuff most of us grow) accounted for less than $2mill in farmgate sales in Vic last year. Huge upside.
Abolone is in terrible strife here atm bc of disease b/n Port Fairy and Geelong. It is decimating the industry and local recirc abolone systems are set to clean up.

SA is number 1 in Australia for $ value production, (tuna.) Victoria is last, even behind NT. Tassie has a massive industry, miles in front of Vic and just behind WA and SA.

After a recent mechanical failure, sleepy cod were found to be (barely) alive at a DO of one quarter of one ppm, at just under 27C. Believe it or not they lived.

When ordering fish always specify the latin or greek name. A black bream is not always a black bream but is ALWAYS Acanthopagrus butcheri, etc.

There is much more "stuff" in our fishwater than we think. This is always competing for oxygen with the fish so obviously we need to look harder at what is in our water, what may attach to the inside of pipes for example and how we can up our DO.

You CAN def have too much DO. It shows very early in snapper which get bulgy/puffy eyes. Apparently they are kept for this very reason as a canary if u will at the Melbourne Aquarium. If snapper start to get bulging eyes they ease off on the O2.

Interesting chat about the global depletion of fishmeal stocks as a source for aqua feed. Peru supplies most of the global fish for stock feed,(pilchards/whitebait/sardines.) They have massive upwelling deepwater zones close to their coast which by definition are highly fertile food sources. During the recent El Nino, their water temp jumped, no fish and global fishfood prices went thru the roof. Obviously massive room for alternative food sources here. BSF anyone?

They plan to run a specific Aquaponic course next year.

Lotta basic stuff i know, but i find it interesting, hope others do.

filip, pm me, so i can give u that tank manufacturer's ph no.

always good to have this information repeated TT

Hey TT, how'd you go with the secret purchase?

Thanks for the update TT

Yes thanks and keep it comming very good information.

Man i didn't even realise it was TT posting! damn avatar change! i only look at picutres

very good info

Thanks all.
Rupe the secret purchase came down to a choice of what i need NOW (plug and go float switch, $90) or the bathtubs i MAY need in 12months, (had agreed on the 20 for 100 bucks.) I am sure u would understand how hard it was to let that little bargain pass me by!

Steve, if u only look at pics, i have a shed full of old magazines i am happy to send u. (I need the space for my fishtank.)

Happy to continue with the update snippets if people don't mind.

Plug and go float switch $90 jees you got to much money nightingales $6.00 bring it to me wiring nothing

thanx 4 the offer FF, u could be a chance next Tuesday.

I'm a "Yes also - keep the blurb going TT
...as for the old mags, Steve only recently married so shouldn't need that sort of stuff just yet....handy for later maybe

Week 3

lotta basic water quality stuff, playing around with fancy $1500 water probes etc. In no ptclr order:

If u intend to seed ur system with dead fish to get the baccie going, don't leave ur dead fish in the fish tank. Put em in ur biofilter/gb. In the fishtank, the stuff that breaks down that fish will cause a depletion in DO and stuff up ur water parameters.

If u have 100 fingerlings at 2g each, (biomass 2kg), they will draw more O2 than 1 fish weighing 2kg.

The warmer the water, the lower ur max DO potential. So you may be able to keep x fish happy at 22C in a 1000lt tank, but if the temp is eg 26C, you may need to reduce ur fishload to keep things in balance, (or add air.)

Given the above, warm water finfish like jades have a greater tolerance for lower DO than say rainbows.

As water absorbs CO2, you get a drop in pH. During the sunlight hours, plants produce oxygen, at night they respire CO2. This has important implications for AP. We need to have active pump cycles overnight to offset CO2 production and hence O2 depletion, by our plants. In a hydro setup for example, if u didn't pump over night and fed early in the morning at ur first pump cycle, u would have O2 depleted water coming back to ur fishtank at feeding (which lowers DO). This may reduce O2 levels to unsafe parameters in ur fishtank.

pH is affected by fish respiration, (CO2 is produced, which wants to drag ur ph down.) 100 fingerlings at 1 gram will have a higher respiration rate than 1 fish at 1 kilogram. U Therefor get a much greater pH swing with lots of small fish so need to monitor this more frequently, than a few fish in the same amount of water with the same total biomass.

If u have a pond rather than a tank enviro, it needs to be located to take effect of prevailing wind. > wind more aeration naturally, less reliance on power.

pH drops with feeding, active fish produce CO2, pH drops. If u have a good carbonate buffer in ur water, this will offset the tendency for pH to drop and maintain a consistent equilibrium for ur fish.

We did some basic water tests and found some interesting observations, particularly in relation to DO. We found 3 distinctly different levels of DO in the same 2000lt tank. Highest DO was in the middle above the airstone. Next highest was on the edge of the tank, at the bottom, just after the water inflow line. The lowest DO level was at the water surface a metre past the inflow line. The variation overall was about 15%, nothing for us backyard guys but vip at commercial levels.

The week prior, they had graded and split a murray cod tank. They got 214 kg out of a 2000lt tank,(107kg/cubic metre)with no supplementary air!! All their tanks are linked, and many were empty so it is thought that the system had evened itself out which meant even tho they had super high levels in one tank, the system as a whole was able to cope.

After grading their black bream from WA a month ago, the fish have taken off. Purchased at 1gram earlier in the year, these guys are now at 25 grams and growing b4 ur eyes.

Niloc, their cats came from rmit and b4 that a supplier in NSW (whose name has been lost in the mists of time.)

Apparently this course gets u half way towards ur cert3 which is a precursor to the diploma course, so if ur thinking of having a crack, enrol for next years intake.

Havin a ball....

Sounds great TT.

...shouldn't that be 1,000 fish @ 2g = 2kg

Good info TT

my bad Ell, sorry. I guess it just reinforces the point, more small fish at same weight as fewer big fish is a bigger strain on the system.