Outdoor system during freezing winter

[novakdav]

Hello everyone, I am considering to setup an aquaponic system in middle Europe where tempereatures get far below zero during winter. I am trying to find out whether I would be able to keep fishes in higher densities alive.

 

I can protect the fish tank from freezing using permanent oxygenation  or a pump, but I am worried about the nitrification of amoniak in cold water. It would be possible to create submerged nitrification filter, but the bacteries activity might be significantly reduced by cold water. Are they? Or the cold water slows down also metabolism of fishes and amoniak wont be an issue?

 

Any advice on that? In case the only solution would be rise fishes from March to October (that should be sufficient for rainbow trout) and limit fish density through winter, I am still worried that turning on the system in spring might couse serious health issues before both bacteries will colonize the grow beds.

 

Thanks a lot for your comments!

David

[Johann]

in middle Europe where tempereatures get far below zero during winter.

Is the below 0 in Celsius or Fahrenheit? 

Below a certain temperature, the fish will not eat as much or stop eating all together, so feeding need to be reduced or stopped.

Bacteria activity will stop below a certain temperature and if the temp is to low the bacteria will die.

Here is a webpage about bacteria.

http://www.bioconlabs.com/nitribactfacts.html

[novakdav]

Hello Johann, I had celsius in mind, sorry for not being clear. Thanks for the link, it is obvious the bacteria will die through winter without special arrangements and therefore the fishes might suffer during the system reactivation in spring... Any ideas?

[TCLynx]

In low density ornamental ponds, fish can survive winter as long as you keep the surface from completely freezing over.  The fish will stop eating below a certain temperature and they shouldn't be fed again till the water warms up to a certain point in spring.  The bio-filter will be moving slow in spring too so feeding will need to be brought up slowly in spring while keeping a close eye on water quality.

 

I don't know how much fish density you would be able to keep alive through winter in this sort of hibernation mode though.

[Johann]

Where in europe would it be? What measurement do you want, metric or in us-standards ?

What comes in mind right now , would be to buried the fish tank in the ground with the top of the fish tank being about 30cm/1ft below ground surface. Put an internal bacteria filter with an mechanical pump and a small air-pump with it.

Then I would leave a 30cm/1ft edge/space and put 1 row of bricks around it. Then cover the the tank and bricks with glass. Make sure you put the air-pump inside the glass works where the air stays warm/warmer. The bricks in Germany have a honey-comb design which will act as an insulation. ( The houses in Germany are build of bricks, but the do not have an extra insulation since the honey-comb design acts as an insulation).The bricks come in 30 cm and 36 cm thickness; also they do have a 15 cm but they do not insulate that good. 

You may want to check what the ground temperature would be in that area. But if you go deep with your fish tank, it would keep the water from getting to cold and from freezing and the nitrifying bacteria may survive. The glass would warm the surface of the tank and would warm the bricks when the sun is out and at night will give off heat. You may want to paint the inside of the brick with a light coat of black flat/dull paint so the brick can absorb more heat.

I would do the glass cover in different sections, with 1 section small enough to feed the fish and to check on them. Europe gets snow and this can be at your advantage. If it gets to cold it may be better to leave the snow on the glass covers as the snow will be acting as an insulator from the cold outside air, but I would keep the feeding cover cleaned off.

Also, if the fish tank is in ground, a small heater could be enough to keep the temperature high enough for bacteria and fish, since the ground would act more like an insulator and heatloss is held at a minimum.

I used to live in Bavaria, Germany and our basement used to stay at about + 17C temperature all year round without using any heat in the basement.

Winter time the lowest outside night temperature would go down to -15C, but not lower than that. Snow accumulation could be 30cm or more. Ground freezing down to about 10cm.

The highest temperature I ever had was 30 C in the summer, but this is very rare like finding gold in your back yard.

The grow beds I would drain with arrival of winter, and then restart in spring. Since you you may have a established fish tank with an internal bacteria filter system that may survive the winter, all you have to do, put the grow beds in line with the fish tank in the spring and nature will populate the gravel again. 

But watch your feeding wintertime.

 

[novakdav]

Thanks for the ideas! My house is located in Czech republic (close to germany with almost the same climate, we use metric measurements) I already plan to have the fish tank 150 cm deep in the ground to keep as stable water temperatures as possible. The idea with glass cover through winter is very smart! I hope that the bacteria activity will fluctuate in similar pace as metabolism of fishes and the system will be therefore sustainable with 5kg of fishes per cubic meter of water, which is amount I would like to keep through winter.

 

I already ordered some literature about trout metabolism of trout in order to properly plan feeding rates according to water temperature.

[Johann]

Feeding rate chart per fishchow.com

http://www.fishchow.com/trout_chart.html

Thanks for the ideas! My house is located in Czech republic (close to germany with almost the same climate, we use metric measurements) I already plan to have the fish tank 150 cm deep in the ground to keep as stable water temperatures as possible. The idea with glass cover through winter is very smart! I hope that the bacteria activity will fluctuate in similar pace as metabolism of fishes and the system will be therefore sustainable with 5kg of fishes per cubic meter of water, which is amount I would like to keep through winter.

 

I already ordered some literature about trout metabolism of trout in order to properly plan feeding rates according to water temperature.

[Jon Nose]

An idea to incorporate into your system to keep it warm
http://www.youtube.com/watch?v=qtFvdMk3eLM&feature=relmfu