Hello aquaponics growers.
This is Jonathan from Melbourne Aquaponics.
My aim is to help you to grow sustainable, healthy, and tasty food in your backyard,
thanks to aquaponics.
So today, I would like to talk about cold water aquaponics.
So what is cold water aquaponics?
So when we talk about cold water aquaponics, we generally talk about aquaponics that is
applied in cold countries.
So cold countries is anything that is below 15 degrees Celsius.
So just to give you a bit of an example, where I come from in France, I come from the border
to Switzerland on the very East part of France, close to the mountains, and there the temperature
can fluctuate and the range is very wide.
So in winter, we generally go below minus 25 degrees Celsius and the extreme we have
is minus 40 degrees Celsius.
So you see that it can be extremely cold in winter, but in summer, we can have plus 30
and very often plus 40, as well.
So you see it goes from minus 40 to plus 40 degrees Celsius.
So you've got a very, very wide thermal range, and that's where we're going to work in aquaponics.
Obviously, in summer, we're going to be in warm water but in winter, we're going to be
in cold water, but is aquaponics really working in cold water conditions?
The challenge we have with aquaponics is that when we got cold water temperature, the bacteria
are going to work very slowly, but also the activity of the fish is going to be very,
very low.
So the fish are not going to grow fast and also the vegetables you know that the plant
they need a certain temperature and if the temperature is too low then you are not going
to have any significant growth on your vegetables neither.
So now the trick is to select some very adapted species.
So what type of fish are adapted to cold water aquaponics?
I will recommend in cold water countries to work with trouts, with carps, or with any
specific fish that is able to grow in those conditions.
So for example, you’ve got also some types of catfish that are able to grow in cold water
conditions.
You’ve got some species of crayfish that are able to grow in those conditions, as well.
So you need to find the adapted species.
So look in the area where you live what type of fish are growing in the rivers, what type
of fish are the fish farmers growing, and that's basically what you want to grow in
your setup.
So as you understand, if the temperature is very low, we are not going to have any growth,
but the challenge is to maintain our system alive so that in summer, we’re going to
have a growth for a few months.
So obviously, the productivity of a cold water aquaponics is never going to be as good as
a warm water aquaponics, but what we want is to keep the system all alive during the
coldest month of the year to boost the productivity during summer.
So during those cold months in winter, there are different options.
I seek two real options.
One is to basically try to maintain positive temperature because you know that the water
below 0 degrees is going to freeze.
Right?
So it's going to form a block of ice, and there your fish are not going to be able to
survive in the ice.
You know they need water to live.
So that's the challenge we have in cold water countries especially in extreme, extreme weather.
When the temperature is negative, we need to maintain our water temperature positive.
So you can do this by first, put your tank in the ground so you're going to have an insulation,
thanks to the earth around, and it's going to limit the water temperature to drop dramatically.
One thing that is very important is to grow your aquaponics into a greenhouse inside to
avoid the wind and to avoid the extreme cold weather to be in contact with the setup.
So greenhouse, fish tank either in the soil or put a very good insulation around the fish
tank, and then if you can, you can heat the system.
So there are different ways.
If you have a greenhouse, you can heat inside the greenhouse, but unfortunately if you use
conventional methods, you may have some trouble to stay, to remain sustainable.
You know there is no point using a lot of gas, using a lot of electricity to maintain
the setup if it costs a lot for you in terms of money but also for the environment.
So what we want is to find a sustainable way to maintain the system more.
One of the good ways to do it is to use a compost heater.
A compost heater?
The idea of compost heater is that you're going to have the pipe that is coming from
the fish tank is going to go through the compost so the pipe is going through the compost and
you know that in the compost you've got this reaction depending on the type of compost
you are doing, but if you have a fermentation, it's going to release some heat and in this
case the heat can be absorbed by the pipe.
So the water going back into the system is heated and therefore, you can heat your system
completely free, thanks to this type of mechanism, thanks to the compost heater, basically.
So then the water that is coming back into the grow bed is a bit higher in terms of temperature.
In this case you can maintain a positive temperature as the target is to maintain the temperature
above 10 degrees because that's when you start to have a growth of your fish especially for
trouts.
Even the carps and most of the fish below 10 degrees you know most of the time they
grow very slowly while above 10 degrees above 15, it's even better, but above 10 degrees
they start to have a significant growth.
So in terms of greenhouse, it can be interesting to work with a climate battery greenhouse.
Okay, and what is a climate battery greenhouse?
So the system is working in this way.
You know that in the day sometimes you got the sunlight so the temperature in the greenhouse
increases, but then during the night the temperature falls, and that's where you're going to have
the big fall in temperature in your greenhouse and therefore in your water.
So the idea is to basically average, balance the temperature between the day and the night
and a climate battery greenhouse is basically going to trap the temperature.
Basically, it's going to blow the air from the greenhouse inside the greenhouse during
the day.
It's going to blow the air in the foundation of the greenhouse.
So the concrete below the greenhouse is going to absorb the heat and during the night, it's
going to do the same thing.
It's going to blow the air underneath, and it's going to raise the air in the greenhouse.
So basically all this temperature, all the heat that was trapped during the day is released
during the night.
So in this case you really average the temperature and you avoid a big drop of temperature during
the night so in this case, you avoid to drop the temperature in your greenhouse.
So it really helps to average the temperature in your greenhouse.
Now, if you are in a low budget and if you are just starting aquaponics, what I recommend
to do if you don't have the possibility to have a greenhouse and you know it can be quite
expensive, is to basically have a productivity that is going to be significant only in summer
and in winter you just want to keep your system alive but what happens is the water freezes.
Can the fish survive?
So here’s the challenge will be to keep the fish alive during winter and therefore
what we want to do we want to avoid to have the whole depth of the fish tank that is going
to freeze and it's going to form an ice block.
What you want is to allow a bit of ice on the surface but no ice on the very bottom
of the tank.
Right?
You want to keep water on the very bottom of the
tank.
So the idea here is to just try to preserve the structure, to work with very low density
of fish, and to leave the fish in the tank during winter and that's fine.
You know in the lakes the fish are in the water and the top of the lake is frozen, but
underneath there is water and the fish are remaining alive.
Right?
So the water generally is below 4 to 0 degrees so it's very cold, and on the top you got
a layer of ice.
So the idea here is to preserve the fish tank because you know that when you're going to
have some ice that is going to be formed on the fish tank, you know that the ice is taking
more volume than the water.
So it's going to create a large, a very strong pressure on the walls of the tank, and if
you have fiberglass tanks, it's going to damage the structure.
It’s going to break them.
Plastic tank is the same.
And even if you got a wooden structure, it can really damage everything.
So what we want to do we want to put some floats in the tanks same as they do in the
swimming pools.
You know those floats you put them on the surface and basically they're going to absorb
the pressure of the ice.
You know when the ice is putting some pressure on the side of the wall basically the floats
are going to absorb this pressure, and it's going to minimize the impact on your tanks.
So it's very important to do that if you have an aquaponics setup outside in cold water
conditions and especially in winter you want to avoid the top to freeze and to break the
whole structure.
So putting the floats is really going to help.
Regarding your pump, you know that you have a pump in the fish tank that is raising the
water to the grow bed.
This pump you're going to stop it during winter because if the pipe freezes, the pump is going
to break, but also the pipe if it freezes it’s going to break as well.
Right?
It's going to be full of water and when the water expands it’s going to break the pipe.
So what you want you want to turn the water off so then the pipe is going to be empty
and therefore you are not going to have this problem of having the pipe that breaks.
You can even remove the pipe from the water.
It's going to be even better.
It's going to allow you to preserve the pipes during the coldest months.
So when you know that you're going to be negative temperature, you remove all the pumps and
you just leave the setup as it is.
If you have some hardy fish that don't consume too much oxygen in low density, they're going
to remain alive underneath the ice for the coldest months, and as soon as the warm weather
is coming back so when the temperature is becoming positive again, then you can put
everything back and you can turn the pump on and you are ready to go for the good season.
So because we are in cold water, we may have the top of the fish tank that is going to
freeze.
Right?
So what you want to do if you work in those conditions, you want to have a fish tank that
is a bit deeper than the norm to keep a very good volume of water not frozen below the
ice, underneath the ice, and there you're going to have the fish that are going to be
able to survive.
Also another thing that can be interesting is to basically raise the pump.
You know that normally in aquaponics, we want the pump as low as possible because we want
the pump to be able to absorb all the feces of the fish, all the you know all the particles
that can be in the water, and you know that the particles if they are heavy, they're going
to fall down in the tank.
And that's why you want the pump to be able to suck them, but in cold water aquaponics
when you are in very extremely cold conditions, what you want to do you want to leave the
very bottom of the tank quiet.
You don't want to create too much water movement on the very bottom.
In this case the fish are going to be on the very bottom and because the cold is coming
from the top you know with the exchange with the air and the water, the top is going to
be very, very cold.
It's going to be frozen.
You can have the ice but on the very bottom you can keep an area where the water is not
moving too much and you avoid the exchange of temperature between the surface and the
bottom of the tank.
In this case it's better to increase the height of the pump a little bit so instead of putting
the pump on the very bottom of the tank, if you have a tank that is one meter deep, you
put your water pump at 50 centimeters high.
In this case you’re going to have the water circulation on the top but on the very bottom
you're going to keep 50 centimeters of water that is not going to move too much, and thanks
to the insulation you have with the soil if you are in an underground tank, or if it's
very insulated, thanks to some whatever cardboard and polystyrene foil and whatever system you
use to insulate your tank then you're going to be able to keep the 50 lowest centimeters,
more quiet and better for the fish.
So you want to avoid too much movement in your water for cold water extreme conditions
in winter.
Another trick you can use is to obviously cover your tank especially during the night
because you want to avoid the maximum exchange between the air and the water.
So obviously, you understand that you are not going to produce as much as in a warm
water aquaponics setup, but the idea in cold water countries is to have a production during
the warmest months and to maintain the system in good conditions during winter.
Now, if you have the ability to work in a greenhouse and to use the compost heating
system or any other system that is sustainable, it can be solar.
You got different options.
Then you're going to be able to maintain good conditions during all year round.
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Have a good crop!