Backyard Aquaponics
A place to discuss aquaponics

My system is now enclosed in a greenhouse. Last night outside temp got down to 32F. During the day inside temp was 82F and that was during a partly cloudy day.

Do any readers think that the water will hold enough latent heat to keep things healthy through the night?

Here's my system before enclosure.



The grow beds fill and empty about 4 times per hour.

Nice looking system!
I'm curious to hear how well you do enclosed in the greenhouse, that's something I've wanted to fool around with next.

I think that it is going to be inadequate, from a heating standpoint, in the dead of winter for 4 weeks or so, and much too hot in the peak of the summer, thru July and August. The summer part I can pretty easily tackle with sufficient airflow. Winter is my bigger problem.

I have plots of water and air temp in my system thread, and from what I can see of your system, you will have a lot more variation in water temperature than I have, due lot a lot more surface area per volume of media and water, and a smaller volume of water. I have about 6000litres, with buried FT and ST.

I have about 2270 liters, 1250 FT and 1041 in buried sump so the temperature variations will be either wider or more frequent (or both) because I have less volume than you. I will need to put a sensor in the FT and record and plot data over time to really get a feel for what is going on.

It looks like you have access to some free firewood.

Perhaps a little cast iron heater?

Or collect and store as much heat as you can in a barrel of water during the day, then let it escape into the growhouse over night

grow beds are really good heat exchangers

Insulating that IBC very thoroughly would be the first step in reducing temperature variation, along with the GBs, which unfortunately have a large surface area for their volume- bad news for retaining heat. You may be able to minimise overnight water circulation in winter to help a bit with that though. If you aren't heavily stocked, just keeping the FT well aerated with no water pumping may be ok for the fish.

Re logging your water temp, I'm very happy with my wifi logger from here: http://www.filesthrutheair.com/category ... ta-loggers
I upload to the cloud every hour and can view it on my computer at home, or the phone when I'm away.

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I was wondering if it would help to make a solar water heater, with the heat-storage-barrel well insulated, and have a coil of plastic hose from a separate air-pump feeding the protected FTs at night..
Ie. Heat the FT at night via warm air.
A thermostat can turn different air pumps on to maintain a reasonably constant temperature..

As GG would say... better to have a phase change material that will actually store more heat, and one wonders about Coconut Oil that solidifies at 22C.. ( problem... Coconut Oil is rather expensive. Settling for anti-freeze for cold climates might suffice)

How practical do you see that Gordon..
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Guys his temperature is already down to 32f over night. Essentially that is 0c. When winter really comes the temperature will really drop.

You don't have any photos of the GH covered have that been done yet? Rather than insulating the components of the system insulate the GH. If you have covered the frame in plastic add a 2nd skin or even a third skin. The energy you will save from expending a small amount on the fans to inflate the additional skins will be relatively massive.

Insulating FTs burying sumps and the like does help but often not anywhere near as much as controlling the overall GH environment.

Indeed - Temperature will be a smallish issue

I thought it was more moderate an area..

So unless you can keep the whole shebang moderate, then keeping the FT warm overnight will come to a cool welcome in the day when you turn on the feed to the GB's

Oh well - So much for climate change..
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I do have access to lots of wood. I have an old cast iron wood stove. I decided against it because of the sparks/embers from the fire. They have a tendency to melt holes in the plastic that the greenhouse is covered with. I can try to put a screen at the top of the chimney pipe and see how that works out.

Phase change materials are great for storing heat, but water is much less expensive, and much easier to obtain- you just need a container and heat source. There are other suitable sunstances which are less expensive than cocunut oil though. However, the temperature and snow graphs you posted suggest to me that there could be weeks of minimal or no sun in winter, so a solar heater may not be of much value.

I don't think trying to heat the water with warm air is worthwhile, as air has such a small specific heat capacity cf water, and it is also a poor conductor, meaning you may not be able to transfer much of the heat to the water.

It seems to me that you should aim to be growing cold water fish such as trout, which could probably survive all year if you can minimise heat gain in hot summer weather.

Understood. I will try to source some trout, they don't grow as quickly as tilapia though, do they?

Trout grow pretty fast, no idea about Tilapia. My Rainbow Trout grew from fingerlings to good plate size in 6 months.