Backyard Aquaponics
A place to discuss aquaponics

Hi guys, how many aquarium heaters do I need to keep the water at about 20-22 degrees.
The guy at Glenwaters said that Murray cod like the water a little warm when weening them on crumble. He said they come partially weened already but will require more training etc.
I am keeping them in a 1000 litre IBC.
Any suggestions on how many and what type and where I can get them will be greatly appreciated.

Thanks in advance for your time.

Impossible to say without more info, as it is entirely dependent on how fast you are losing heat from it, and what you gain during the day.

How much does it cool down between 17:00 and 8:00 on a typical night ATM?
How much does it warm up on a typical day between 8:00 and 17:00?
Is it insulated?
Is it indoors?
Is it exposed to much sun during the day?

Hi Gunagulla, I am in the start up process, just getting all the equipment now.
It will be outdoors, not in sunlight, covered area or shaded if u like.
It is an Autopot system so the water from grow beds does not return to FT it stops at the plants.
FT. Will not be insulated.
I have read varying posts on here, some say 1000 watt heater should be enough.

+1 on Gungulla, but it won't be cheap.

I got told the same thing with my Murray's, I think it's code for we haven't weened them, have fun trying to feed them.

This is the first I've heard of the autopot system, it seems horribly wasteful, from what I'm reading, you pump water in, that water overflows into the pots, and is wasted? No filters, just new water flowing in continually? It'd work, but you'd need to use a lot of water.

6 hours per day with a 1kW heater should make up for ~5C loss, but you could cut that down significantly by insulating the tank.
How much does 1 unit of electricity cost you? At say 30c, its going to cost nearly $2 per day if you are trying to make up 5C loss overnight in cold winter weather, which could be quite expensive over a few months.

Is the water circulated through a filter, with some going to the GBs when required, and that is replaced with top ups from the tap/rainwater?

For a start you will need filtration on your ibc as you can not run an autopot system on un filtered water
If you look at jims setup you will see a uv filter also he is running it through that big banana tree that is removing the nitrates
You need to take into consideration when you run through a filter bed it also cools the water
Auto pot jim isn't just running his auto pots on fish water he also adds his own a and b nutrient mixture
Oh yea good luck on getting the cod on pellets

Google auto pot systems
It doesent flow in and get wasted its probley the most efficient use of water there is under the right circumstances and applications

Yeah mate, the water will be filtered and attached to mains supply.
I will be using a dosing unit to also add nutrient A& B as well as water from FT.
Very good system I'm told.

http://autopot.com.au/content/documents ... 7.2008.pdf

That's the one I was looking at.

But it's just a sock separating the solids (no problems if it had proper water filtration, like an AQ setup, but it just looks like a sock taking out the solids), and circulating the water through the tank.

If you had really low stocking density, I could see it working, but to keep the ammonia down, I'd imagine it'd need a high turn over of water, and there is only so much the plants could take up.

I could be overreacting to it though, it's the first I've heard of it.

Just don't believe all your told
Jim at Buninyong was using that idea he now has gone back to his own mixture hydro and you should see the plants now

Thanks mate for info. I will definately be running a filter, Jims rig has blown my mind.
Oh, everyone is wishing me luck on feeding murray cod with pellets, is this code for you don't stand a chance, haha?

My fry/fingerlings were supposedly pellet trained, but I never did get them to eat pellets, and after much expense feeding them blood worms, then ox heart over 15 months, they were mostly disappointingly small, and most of the remaining ~30 died recently, leaving me with just one, which is about 20cm long... and still not eating pellets.

Oh, I started with 150 of them- many died early on due to not eating anything when pellets were offered, and the big ones got big by eating the smaller ones.

All I can say is: good luck!

As above, really the question should be how much insulation do I need!

I'm currently building a 2 IBC RAS based system for my barra and reckon I should be able to get away with a 200W heater based on the heat flux calcs. I'm fully enclosing 2 IBCs and 2 x 200L barrels in 150mm EPS coolroom panel so top, bottom, front, back and sides will be insulated. Thats based on 24 degs water temp and an average outdoor temp in Winter of 7 degs (at worst).

So I'll be building the system with a 200W and a 500W heater and see how that goes. I'll also put the air pump inside the enclosure so any heat generated from that will be recovered - hopefully it won't overheat!

Thanks guy's for the info and advice, much appreciated.

We'll see how it goes. Fingers crossed.

Did you have the water heated between 20 - 22 degrees? The hatchery guy at Glenwaters said to get them to take pellets the water needs to be about 20 degrees or they wont even look at it.