Backyard Aquaponics
A place to discuss aquaponics

Hi.

I'm wondering if anyone has implemented a cooler for their AP fish tank?

My trout were late coming in and I had some issues later where I couldn't feed much means that they are still quite small. I'm keen to keep them in another month.

I have a 1400 L tank, so a regular chiller wouldn't work. I'm about to get an old bar fridge, put a large tub of water in it, run some pipes through the door into copper coils in the tub. Pump the tank water through this and back to the tank.

Any thoughts?

Also, is there any point dumping large ice blocks (like 10L) into the tank. Would make no difference on a hot day right?

Don't pump you fish tank water through copper pipes... copper leaching will kill your fish...

Icing your tank can help.. marginally... see Gungulla's thread...

And not pumping through your grow beds during the day.. can help as well... IF you have LOTS of aeration... and only IF...

I know it's been tried using the smaller 1.7 sq' fridges with fresh and salt water fish tanks. It did work, but it was all about the mass of the chilled water in the tank. Most of these units do not have a real thermostats and caused other issues.

I think of an old bar fridge as a 8' long fridge that bottled beer is kept in or a unit that holds a few kegs. From my younger years as a bar back I know most of them were made to keep cold beer cold and adding room temp bottles was not a good thing unless it was the end of the night.

A large thermal mass of chilled water is a good thing, but you need to look at the compressor and how many BTU it will be able to produce.
Don't forget that the fridge will also be adding heat in to the room that it is in.

Be very careful with icing your tank. It is very easy to over do it and cause huge temp swings that could hurt your fish.

Is geothermal cooling an option where you are? If you can dig or drill or whatever down to the closest water table, it will likely be cool enough that putting a heat exchanger down there will give you a good place to dump heat. Of course you'd want to check with your local drillers, geologists, or ag extension service to make sure you're not just pouring money into a hole in the ground.

Been there tried all of the above the only thing that works is ice at $2.00 a time for ice it soon adds up
Turning off your beds helps a bit
With heaps of air I have had trout to 25 deg no problem

It can work but the size of the chiller you need is much bigger than you would think.

Imagine you want to heat your GH in the middle of winter.

How big a heater do you think you will need?

How big a heater do you have in your house which is much better insulated and less drafty?

Cooling is harder than heating so double the size of your heater to get your chiller size.

Then, since chillers are essentially heat pumps which don't work so well at cooling when inside and outside temps are both hot, double the size again.

In a glasshouse you need a heater of about .1kw/m2. Which by the amputated rule of thumb above you would need .4kw/m2 of cooling.

So for a small 20m2 GH you would need a ~8kw chiller. Aquasonic has a 5kw chiller for about ~$4500.

http://www.aquasonic.com.au/product/1ph ... ill-5-5kw/

As mentioned above, the amount of cooling is much greater than you might think. I calculated 21kWh of cooling required for my system on a hot day a couple of months ago, and it will be significantly more than that once the temps get nearer 40C. To remove 21kWh of heat would take ~150kg of ice! On the hot days I've had in the mid 30s over the past few months I've added up to 60kG of ice in a day, added in batches of up to about 15kg per hour, which does not cause any huge temperature swings in my system, which contains about 6000 litres of water. I have a 400l chest freezer, currently full of blocks of ice weighing 2-4kg, probably about 300kg in all due air gaps between the blocks. The aim is to get me through spells of a few days in the mid 30s, but I wont be able to make ice fast enough once the daily max temps are consistenly in the mid 30s, which is normal once we get closer to xmas.

I use the cooler weather to accumulate the ice blocks, so I'm ready to use large amounts on hot days, a small bar fridge connected to my AP system has no chance of supplying that amount of cooling, with its tiny ~100W compressor. For me, if I wanted to use a water chiller and rarely need any ice, I'd need an efficient chiller system with perhaps a 1HP compressor. I priced an Australian made process chiller the other day- 12 weeks lead time and over $5000! Hailea chillers look enticing with a 1HP unit for not too much over $1000 if you shop around but I really have no idea how reliable they might be. Teco looks better on paper, but are significantly more expensive, so for now, I'll see how far into December I can keep the tank cool using ice.
The most useful way to keep your system cool is to stop it getting hot in the first place- this means lots of shading, and as suggested previously, reducing daytime water circulation. Have a look at my system thread for temperature plots.

I can only think of 2 ways to dump heat cheaply (and the proviso is that you are in a dry climate).
The first is evaporative and the second is to dump it to the night sky with IR. (with the second you would need to be able to "store" it )

Evaporative certainly helps- I've tried raising my flood level to the surface of the GB on a hot day and it certainly helped with cooling, but did use a fair bit of water, and killed off a few of my lettuce. It wont really cool to below about 20 or 21C though... but that's fine of you are trying to keep trout alive.
Dumping via IR to the night sky works too- but leads to a larger diurnal delta T (change in temperature), which the fish may not be all that happy with.

If we are talking about cooling a FT with evaporative you can go two ways, ask Rupe about a bakki shower, you could even use a blower on the side. Or set up a custom built heat exchanger that uses misted water and evaporates every single bit (phase change) probably with a blower. Heat exchanging from the GB's is not a good idea.
As I said with IR you have to "store" the cooled water to be used during the day.

I have cooled my troutz in the freezzer

You have silver perch options in a few weeks if not now Torcz.
Or run it hydro over summer with Charlie carp and other stuff.
Get in early for trout next time - we can buy together again - I still have 2 half bags of feed left.

Thanks for the replies.

I currently run the GBs at 15/45 during the day and 30/30+ at night. My tank is dug into the ground, so I'm still running ~15, but its getting close and there is a stretch of 30+ days coming up. I had two die yesterday due to the heat..

I was planning to actively regulate the flow of the pump through the fridge vs the water temperature to avoid fluctuations. Looking at the above comments I think I better just keep it simple.

So I have a few trout that look around 400g then the rest are probably 250 - 300g. What should I do with these? Whats the minimum weight for eating? I was planning in smoking most.

250-300gm are fine for smoking...

How warm did your water get, and how much aeration did you have?