Backyard Aquaponics
A place to discuss aquaponics

My strongest memory of the Eel-Tail Catish (or Jew Fish as we called it out west QLD) was as a 15yo having my hand slide down the blade of a filleting kinfe trying to skin it. Ouch..... took me a week to find the knife after I threw it. Had the scar for years afterward.

My dad always said it wasn't the best way to test the sharpness of the knife, when I cut myself. He is sooo compassionate.... not...

did you learn quicky TC

Hi Folks,
I am now at the almost ready for gravel washing- about 5 or 6 tonnes of the stuff- plan on using a big cement mixer on the back of my tractor.
At this stage I think I will probably have Tandanus tandanus (eel tailed) catfish as they 1 . available and 2. likely to survive the low temperatures we get here , near Canberra. The fish tank has been full of water for 5 or 6 days and seems to be stable at 11 C. The system will be flood and drain using a 15000 litre per hour sump pump and remote float switch. Planning on pumping for about 7 or 8 minutes per hour- rest of the time draining.
The pictures show the lid still on the fish tank- this will be removed when I have fish and have made another cover to keep miscellaneous beasties out and the fish in.
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nice stands Jim

I recognise those growbeds !!

Hi Stu,
Yes they are the same team poly units you have. BTW took more than 4 months for them to be delivered. And the tank took another 2 weeks!!
After making the stands I disc over that they are a little too big- however I plan to wrap the growbeds with some sort of insulation so the extra size will not be wasted.

room to sit your beer!

As I have posted before I live near Canberra where the winters are cold! At the moment it is 2.8 degrees outside and while the North American members probably don't think that is cold we all know that any fish we want to grow do think it is cold. At the moment this cold is putting a complete hold on further work on the system with the exception of my plan for heating the water.
So I have been planning , mostly in my head, a heater for my fish tank (4500l buried almost completely), which is completely solar powered.
I have a couple of old solar hot water panels, about 25 years old but still working until removed from a roof about a month ago, given to me by a mate.
I have also managed to find a 12V pump (Davies Craig EBP) which will run quite well from a 10w solar panel (also in stock) Might need to add an ATA maximiser to ensure proper pumping.
My plan is to use a glycol solution and heat exchange mechanism so that I don't have to worry about the panel freezing and also to minimise the contact the fish water has with whatever might come off the pipes in the panel.
At this stage it is fairly straightforward- make a stand for the Panel, hook up the PV panel, run the plumbing from the heater panel to the tank.
As the pump would only run when the sun shines I don't expect to lose any heat back to the panel at night.
Only one remaining problem- what to make the heat exchanger out of. My initial plan was to simply buy a coil of the 13mm soft copper pipe, which I used when I plumbed the hot water panels on the roof of my house into the heat exchange unit for home water heating, and join it into the loop with compression fittings.
Now the big question is how do I/we determine how likely it is that the copper from the coil will damage the fish. Everything I have read about copper toxicity talks about COPPER SULPHATE which is very soluble in water.
I know that Doug Basberg painted his copper heat exchanger pipes which are in the fish tank. He has had so much trouble that it seems very hard to pin down the source of his fish deaths and so who knows if it is copper toxicity.
My gut feeling is that copper pipes simply sitting in the water should NOT release significant copper into the water. I have also considered having the coil coated with something- perhaps chrome or powder coated - don't want to use paint as that is a whole new can of worms re toxicity.
Has anyone any hard evidence that metallic copper simply sitting in water will dissolve into the water in any significant concentrations?
Is it possible to buy test kits to check for copper in water?
PS this was also posted on "the other" forum without much success
today it is warmer outside but my fish tank is still at about 8.5 degrees C and varies by about half a degree over a week.

Hi Jim ,is this the Jim Atkinson I remember from bega?
This is colin game.

Could very well be Colin... Jim's currently living just south, southwest of Canberra.... not to far from Bega as the crow flies....

What brought you to Bega Colin?

I was born there Rup ,now living in Esperance WA .Gerringongs ok but Esperance is better!

Hi Jim, haven't heard from you in awhile

Yes - you can buy copper test kitsTest Kits - half way down the page for an example.

Copper pipe in water may be okay, but I have had experience with a steel rod in aqauaponic water which rusted out in 2 months and I needed to devise a cover to stop future corrosion. My thoughts are that fish water would do the same to copper

Would be a very interesting experiment to have say a 200 litre tub with normal water and a 200 litre tub with a coil of copper and still water and a 200 litre tub with the same length coil of copper and moving water, to see what sort of readings were to be had. Care to take a hit for the team Jim?

I would think the pH of the water would influence whether the copper would break down. More acidity = more copper? Chemistry was not my strong point in school, but as long as you are experimenting, you might try three smaller scale experiments at 6.0, 7.0 and 8.0 pH. Realizing that fish tanks will go acidic over time, maybe just 6.0 and 7.0.

Jim, janets hit it on the head, i'd say "no way" to using it at ph 6.0 "maybe" at ph 7+.

We're probably being over cautious here, hell i'd love nothing more than to use a roll of soft copper for an exchanger, but i'm not willing to risk it at this stage.

If you're thinking of running any type of yabbie or related animal then just make it a categoric NO!