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kenners

Aquaponics in Melbourne & temperature!

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G'day everyone,

I'm interested to know if anyone is successfully producing any fish in Melbourne out of their system.

I have been doing this for about 3-4 years now, and so far no fish have actually been harvested.

I have 2 setups using IBC tanks. I started out with Tandanus catfish and silver perch in both.

However I was getting a bit 'over' the electricity bills to heat the water during the colder months. I know the natives should survive without heating but then they don't grow and are prone to disease.

After I lost all (25) in one of the IBC's to white spot, I decided to go for rainbow trout - I really wanted to get rid of the heaters! I still have catfish and silvers in the other one.

However, with the 40 deg day yesterday I have so far lost 5 trout.

I guess I'm just wondering if maybe I'm trying to achieve the impossible.

Is anyone in Melbourne - or somewhere with a similar climate (i.e. 40 deg one week then back down to 14-20 the next) actually able to keep fish alive without resorting to expensive heating or cooling of their tanks?

Sorry to sound a bit negative - but the dead fish are very frustrating.... :P

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Hi kenners

I also live in Melbourne and have been doing aquaponics since 2010. I have silver perch and murray cod however they are very slow growing and I have never harvested any of these fish. I have managed to grow out and harvest trout and I am currently carrying 30 rainbow trout. Whether I can get them through the summer will depend on how many successive hot days we get. On hot days I increase aeration using an additional airpump and water pump. You could try increasing your aeration on hot days.

You can always stock your trout starting late March and harvest end November when the hot days arrive. Buy some good sized advanced fingerlings to start off with.

Cheers

Joey

Edited by Joey (see edit history)

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Hi Kenners,

Sorry 'bout the loss of your fish.

I think that, central to the whole business of backyard fish- keeping is environmental control. It's certainly a cornerstone of my Queenslander design.

There's very few places anywhere (the humid tropics being the most obvious exception) where you can grow fish year round without moderating the climate somehow.

I'm not a huge fan of using electricity to heat or cool aquaculture/aquaponics systems - they grapple with sustainability as it is.

For me, it's about housing your fish production system in a structure that enables you to use passive solar/wood/trash heaters to moderate the ambient temperature. It's about limiting how much wind blows across (most importantly) and around your system.

Environmental control is about limiting heat loss and the integration of waste heat and low cost/impact heating systems.

Hope this helps.

Gary

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G'day Guys, thanks for the replies

I guess I should think myself lucky that I only lost 6 out of the 20 trout when the water temp got up to 26.5 and they should only have survived to 22. I think the idea of increasing aeration may be a winner as well. Most of the heat is coming in through the grow beds as the tanks are insulated. I have change the times when water is cycled through the grow beds, and i'm currently making an evaporative cooling tower out of some 100 mm PVC pipe. Hopefully this combination will keep the water at a trout friendly temperature.

cheers

Andrew

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Hi Andrew,

I've not lost any fish yet,and am working on keeping it that way, although 3 days in a row with the water temp up at 30 makes me a little nervous, especially while we are expecting 40 plus 2mrw. i only have silver perch so have a little more room for error. i am interested in your plans of an evaporative cooler using 100mm pipes, could you share your plans. i use a water mister that comes on every hour for 3 mins, but every little bit helps.

Cheers,

Matt

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I have Silvers and Catfish in one tank. Have harvested a number of Silvers. They are definitely slow growing over winter... but they do grow to an edible size.

post-975-13795790776055_thumb.jpg

post-975-13795790776676_thumb.jpg

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Hi guys,

Thats great to see you have got some silver perch out of your system ColinW - I thought it may never happen :P!

Matt, I'll take a pic of the cooling tower and post it over the next couple of days. As an example, theoretically (Dewpoint and Wet-bulb from Relative Humidity Calculator - Weather Calculators and converters - 4WX.COM ? Weather Information Center!) at a R.H of 45% and an ambient of 25 deg, it should be able to bring the water down to 17 deg. I figured if it works, I can switch it on when the conditions are right and help buffer those really hot days. Now I just need to get it to approach the theoretical limit - which will probably be difficult. Although evaporative air conditioners work OK'ish in Melbourne.

If nothing else, the water trickling down the tower will increase the oxygen content of the water.

cheers

Andrew

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Thanks Andrew, I kinda already use an evaporative cooler (ie - misters blow water onto the shade cloth and the breeze does the rest) but this only happens every hour and imo it is a waste of water. Looking forward to seeing your photos, it might be something that i would use.

Matt

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Hi

Melbourne weather temperatures are certainly hard on growing fish without either heating or cooling the water. I believe that a system growing trout, where the fish can be isolated from the growing system and housed in a closed environment, is the way to go.

On hot days the environment surrounding the fish system can then be cooled with an airconditioner, preventing the water from heating up. The cost of cooling for the few hot days we get in Melbourne would be cheaper than trying to heat water for silvers, murray cod or barramundi for most of the year. My fish system is in a shed complete with it's own filtration, however adding an airconditioner is still on my list for things to do.

Cheers

Joey.

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If the air temperature is substantial higher then the water temp (40 degree days), the intensive contact between air and water heats up your water and this will works again the cooling due to evaporation. As an example; a number of years ago I managed a large recirculation system close to Melbourne. This system had large trickling filters which can function as evaporative coolers, by increasing the air speed through those filters. During heatwaves the temperature always slowly creped up even which the fans running flat out. Due to the large volume of the systems the temperature changes were so slow that this didn't result in issues.

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Hi Andrew,

...i am interested in your plans of an evaporative cooler using 100mm pipes, could you share your plans. i use a water mister that comes on every hour for 3 mins, but every little bit helps.

Cheers,

Matt

G'day,

I have finally tried out the cooling tower and taken some measurements.

it seems to be working quite well after some experimenting with the packing inside the column. I'm using two computer power supply fans and a small brush-less water pump rated at about 5 W. The whole setup uses 12 V.

Ambient Temp: 27.7 C

Water Temp: 24.5 C

Water output: 23.9 C (output from tower)

As you can see I'm getting 0.6 C temperature drop.

After moving the packing around a bit I managed to get 0.8 C.

After the cooler has been running for a while you would expect the tank temperature to approach the wet-bulb temp (which was about 19 C at the time).

post-3184-13795790916898_thumb.jpg

Cheers

Andrew

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G'dy Andrew

Your tower looks great and appears to give some cooling effect.

What media are you using for your tower packing?

regards

Brownie

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G'dy Andrew

Your tower looks great and appears to give some cooling effect.

What media are you using for your tower packing?

regards

Brownie

G'day,

Initially I tried fly-wire screen scrunched up. But it didn't work very well. It seems to be more important to not impede the air flow too much - I guess the fans aren't very powerful. So in the end I used the open filter mat stuff that I use in my filters. I roll it up and push it down the tube, leaving the center open to get plenty of air flow.

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Thanks for the info, definately worth a try. I have seen. Similar unit on instructables which was called a bush aircon. It worked in a simmilar manner, however instead of returning cool water it used a small reservoir that cycled water onto a sponge inside a bucket. The bucket had holes in which the fans drew air past the spong through the wall of the bucket and into a small duct in the lid. The initial purpose was to cool your tent down when camping. It used a standard 10l bucket and motorcycle battery. It was capable of running for at least 4-5 hours on a few litres.

i think i may give both a try, epecially since we are experiencing temps in the 40c range.

regards

Brownie

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