Solar hot water - Hot water system

If we create the bottom half of a thermosiphon by putting a black hose into a foam box and cover it with a sheet of glass, we will see the beginnings of a (hopefully) slightly efficient (albeit temporary and largely useless) solar collector.

If we use a large insulated drink bottle to concentrate collected hot water as the top half of the thermosiphon, we will see the beginnings of a temporary and largely useless solar hot water system.

Its night time.

Its not collecting much heat.

It's not very well designed. There are bits where the tubes form loops, and all tubes go down in through the top. My head says it should work a bit. The rest of me is not so sure.

We shall see when the sun next shines.

Aquaponics - Home made media

I did an experiment last night where I mixed some clay soil from my backyard with some crushed up goat dung. The plan was to try to make something like scoria, for use as a home made media for a grow bed, but just to see if it could be done.

And voilĂ !

First, I spread some whole dung out on a tray. Then I made a mixture of clay,water, and powdered goat dung. My theory was that the powdered goat dung would create thousands of tiny holes in the finished product. This would create some happy housing for the nitrifying bacteria required by aquaponics.

I then poured the mixture over the tray of whole dung. The design behind using the whole dung was an attempt to make it break into irregular shapes later on in the process.

Next I set it out to dry. If I was making an amount greater than this tiny test, I would have poured it onto the ground in the sun. But it was raining so I put it on some foil, and dried it on the fire. DONT DO THIS AT HOME! It can smell a little agricultural. When the yelling stops, you know your tile is dry.

Lay it out and build a fire over it. You want your fire to be 900 deg C or more. Clay will undergo a permanent chemical change at around 600 deg C (don't quote me on that number) where it becomes no longer possible to wet it back down to clay. The physical water steams off at 100 deg C, but at those higher temperatures its not just drying the clay, it's actually changing it into something else.

I actually fired mine in my living room wood burning heater, but to make it properly you need the kind of temperature that makes iron glow bright cherry red (~900C) It's quite doable in a decent fire.(a match burns at around that temperature).

A normal pot would crack if treated like this but because there is so much organic matter leaving the clay body porous, we can get away with it. It doesn't matter if it cracks anyway.

Next. Smash it.(see)

Its done (see top pic)


I have no idea if this is practical or useful in any way to anyone, but it was in my head so it had to come out.

Solar hot water - Solar collector

A foam box with a sheet of glass on top should make a pretty good solar collector. It is well insulated and the glass should stop any captured heat from escaping. If it's painted matt black inside it should work even better.
To have something to compare our results with I have a second identical foam box. I've placed a thermometer in each, but I've placed the digital readout next to the other thermometer so I can see them both at the same time when I take a photo. The box on the right has the digital temperature probe in a similar position to the other box's thermometer. The box on the right also has some black plastic in it and is covered by glass.

To make sure both thermometers were working and showing the same temperature I put them in the same box for a while.

Both thermometers showed 22 - 23 C in the same box after sitting in the sun for around 20 minutes.

 It was 20.8 in the shade according to a third thermometer. I have a lot of thermometers. 

This was the amazing result after 36 minutes!

+ 45 C in 36 minutes!

I knew there would be an effect but I had no idea it would be as big as this.

Did I mention it only took 36 minutes!

And 68 deg C! That's slow cooker temperature! Is that slow cooker temperature? Yes* it is! And on a 20 degree day! In only 36 minutes! I wish I had some aquaponics produce. I want to make some laksa! 

HACCP guidelines

The UK Food Standards Agency publishes recommendations as part of its Hazard Analysis and Critical Control Points (HACCP) programme. The relevant guidelines at state that:
"Cooking food until the CORE TEMPERATURE is 75 °C or above will ensure that harmful bacteria are destroyed.
However, lower cooking temperatures are acceptable provided that the CORE TEMPERATURE is maintained for a specified period of time as follows :
  • 60 °C for a minimum of 45 minutes
  • 65 °C for a minimum of 10 minutes
  • 70 °C for a minimum of 2 minutes"
Previous guidance from a leaflet produced by the UK Department Of Health “Handling Cooked Meats Safely A Ten Point Plan” also allowed for:
  • "75 °C for a minimum of 30 seconds
  • 80 °C for a minimum of 6 seconds"

Solar hot water - Greenhouse

Anyone who has left a hose out in the sun on a hot day will know how much heat its possible to collect. Collecting heat on a hot day is easy. What we need to be able to do is collect heat when there isn't much around. One way to do that is to flatten out your hose to increase the surface exposed to the heat. The downside to that is you also increase the hose's ability to radiate or lose heat.

What we need is a flat, large surfaced hose that's insulated to prevent heat loss. Unfortunately what we also need is a big flat hose that's exposed to the sun and isn't insulated in any way. In fact what we need is a big flat hose that's both, a conductor of heat, and well insulated.

Some years ago in Rome, someone accidentally mixed a flux of some kind into their beach party's fire. The same thing probably happened in China as well. Some time after that, people started making glass. Others may have a slightly different or more complex  history of glass, but I'll leave it to the reader to decide on their preferred history.

Normally when the sun's radiation hits something it gets warm. If the object becomes warmer than the surrounding environment, the object starts to radiate energy to share the warmth. Heat and light (and microwaves, and for what it's worth, puppies and beer) are all basically the same stuff. There is a very cool characteristic that glass has. Light, unlike puppies and beer, to a large degree can pass through glass. Once it hits something that it cant pass through it is either reflected away or is absorbed. If it's absorbed it is absorbed as heat. Normally when something outside is heated, the heat radiates away and warms up the air or whatever else is around it. This air then rises and disperses away. But you can use glass to stop that hot air escaping, or at least to slow it down. If you used glass in this way you will have built a greenhouse.

It seems to me, in order to make a solar collector, what we need here is some kind of big flat matt black greenhouse hose.

I think I understand the main principles involved here so It's time to do some experiments.

Solar hot water - Thermosiphon

With enough time on your hands its possible to make water go round and around with the power of sunshine.

If you connect one end of a hose to the top of a container of water and connect the other end to the bottom of the container, you will have made a bucket with a loop of hose.

If you fill it to the top with water, shade the end of the hose that is attached to the bottom, and drag the entire contraption out into the sun, you will have made a solar powered thermosiphon.

A thermosiphon is better than a bucket with a loop of hose attached to it.

Because hot stuff rises, the part of the hose that is exposed to sunlight will make the water inside move up. Once the water moves up, some water in the bucket moves down. The water cycles around for as long as the device is in the sun.

The best part is, when the hotter water gets into the container, it rises to the top. This means that its the coldest of the water that flows back out into the hose, and the hottest water remains in the container.

This also means we have collected some solar hot water. Not much and not very efficiently yet, but we are on the right track.

Aquaponics - pH buffering

In aquaponics, one issue that can effect your success rate is the pH of your water. pH is a measure of water's (or soil's or whatever's) level of acidity and alkalinity. A pH of 7.0 is considered neutral and also is what pure water measures.

Actually when we measure pH what we are really doing is comparing the relative quantities of two molecules. The hydrogen ion H+ gives us acidity, and the hydroxyl ion OH- gives us alkalinity.

The process of nitrification is acidifying, but in aquaponics we aim for roughly neutral water around the pH 7.0 mark. Depending on the media you use in your garden beds, your system's pH might not be close enough to 7.0 for your liking. Because the bacteria tend to make their world a little more acidic, the water will dissolve anything more alkaline than the current pH of the water. What this means is, if you have something like calcium carbonate, say in the form of shell grit* in your system, your clever system becomes self adjusting. Shell grit seems to have a pH of around 7.6. The more acidic your water gets, the more shell grit gets dissolved. This brings the system back into equilibrium. The shell grit will last for many years (depending on how much acid there is).

The shell grit is trying to get the water to pH 7.6, and the bacteria are forcing the water toward 6.0. Hopefully the result is your ph settles somewhere near 7.0 and everything gets along just fine. Plants also seem to enjoy a pH of 7.0, and that pH level also allows for the maximum availability of various trace elements to be liberated from the system and offered around to anything that wants them.

Shifting an aquaponics system toward acidity is a little harder. Most people add lemon juice, or vinegar. The test pictured to the left is the one at the top of the page but with 2 drops of lemon juice added. The problem with adding acid is that it would have to be done on a regular basis which is why we need to be careful not to use anything too alkaline as our grow bed media. Some people have gotten into trouble with limestone and marble.

Over the last few days I've been doing experiments with softwood charcoal, and have found it to steer a system toward being more acidic on an ongoing basis. The tests have only been going for a few weeks. The problem of a too alkaline system needs to be avoided from the outset, but if you have very alkaline water (say from a bore) charcoal might be a good way to pre-treat your top-up water and the initial water you use in your aquaponics system.

*shell grit is available for a few dollars a bag wherever you can buy chicken feed. Its made by crushing oyster shells or similar. Chickens eat it for the calcium they need to make egg shells.You can also use egg shells or snail shells for pH control in your system.

Solar hot water - Heat exchange

Some things allow heat to move from them to other things really well and some things don't.

The rate of heat exchange between one item and another makes us say words like insulation, and conductor. The reason people selling you insulation can claim that it keeps you warm in winter and cool in summer is because it does. Insulation achieves this by denying heat exchange between the sun and your house, or your house and winter. A perfectly insulated house would always be the average yearly temperature of your region.(unless you add or remove heat (Actually a perfectly insulated house would always be whatever temperature it happened to be on the day it was built.))

Heat conductors, on the other hand, love passing heat around and sharing it with anything that also conducts heat. An example of a good conductor of heat would be an aluminium cooking pot. Or in my house, copper based stainless steel cooking pots. The reason the copper is on the bottom of the pot is because it conducts heat well and the stainless steel doesn't. The reason the stainless steel is there is due to a scandalous error from within the scientific community, and some ill-informed law. A poor heat exchanger makes for a poor pot. When you heat a pure stainless steel pot the heat doesn't spread evenly and your food burns because all the heat is in just a few spots where the flame or electric element touches it.

If you want to collect heat, it turns out another thing to do is to stop reflecting it. Those silver things people put up against the inside of car windscreens work quite well at reflecting heat, as do white things. Black things on the other hand absorb heat. Matt black is even better.

For 10 years or so, from when I was about 5 years old, we had a black and white cat. Once, when it had been lying in the sun for a few hours one hot summer's day, I remember patting it. It tore strips of flesh off my arms. It was a starving stray when we took it in and it simply hated humans.

If you want to collect heat from the environment, it's best to use something that is good at heat exchange to collect heat, and then its best to use something that isn't good at heat exchange to store it and stop it escaping. If you want to collect heat from a nuclear reactor,  its best to use someone else's country.

I wont be exercising the nuclear hot water option at my house. Although at first glance it seems safe enough, I'm told it's prohibitively complicated and expensive, and could take longer than the two months I've allotted to each project to gain local council approval.

Solar hot water - Heat

There's really no such thing as cold.

Unlike politics, just because it can make you miserable, numb, or even dead, cold doesn't actually exist.
What you are feeling when you feel cold is actually heat moving away from you and toward something else. Things lose heat or gain heat but don't lose or gain cold. Heat is so generous that it simply wants to share itself evenly everywhere. Unfortunately for you, that means if you are warmer then the winter around you, all that generous warmth you make is going to try to spread out to everywhere else.

"My air-conditioner makes cold" I would sometimes hear myself say. "But it doesn't" I might reply. It turns out an air-conditioner is what is known as a heat pump. All it does is finds some heat and shifts it to somewhere else. In the case of cooling, it takes the heat out of your room, and throws it outside where it belongs. In the case of heating it grabs heat from outside and sticks it in your room. That bit is most amazing as far as I'm concerned. Its incredible to think that there is so much heat out there in chilly winter, that an air-conditioner or a solar hot water system can pick up great wads of the stuff and jam it into my house to make me warm.

Thanks science.

Another important and useful thing about heat is that it rises. That's because when stuff is hot the little stuff that stuff is made of move about a lot. This means the stuff expands a bit. When an amount of stuff is bigger than the same amount of the same stuff, it weighs less. Which is to say it displaces more of some other stuff. I'm glad we cleared that stuff up.

Hot stuff rises above its neighbouring less hot stuff. That means we can move heat for free. If hot air rises and we need to move it up, all we have to do is let it move there. If we need to move it up and to the side, all we need to do is put it in a pipe.

Solar hot water

It turns out a stack of energy hits every square metre of the earth's surface every day. Especially in the bits where its daytime.

Pictured here, and using the sun for scale, is an impressive looking graph showing exactly how much that could be. One way to combat such a graph is by collecting solar energy.

Hot water represents a fair slice of power consumed by most people's homes, and as such, is a good place to start. The problem with buying a solar hot water system is all the work you have to do to earn all the money you need. If you make it yourself it still takes some work, but you learn some stuff along the way and save a stack of cash.

The ambient temperature of space is a nippy -270°C (there is no wind chill factor) but the average temperature here on earth is a balmy 14°C. Quite pleasant really in comparison.
All you have to do is figure out a way to pick some up, move it to somewhere else, and add it to what's already there. Do that a bit more and suddenly your bath goes from being potentially deadly to rather pleasant.

Basically there are great wads of energy lying around free for the taking. I'm going to have a crack at picking some up.

Aquaponics - Emu spin cycle

When removing rust and washing your grow beds with a high pressure hose in preparation for rubber painting an auqaponics system, it's extremely important to also make sure your emu is well rinsed.

To begin, give the emu a hint that there may be some water to be enjoyed.

Wait until the absurdly oversized bird has dropped down into some crazy dinosaur footed slowly moving toward you crawl before applying the full force of the high pressure cleaner to your bird.

Ignore anything that looks like your emu's head has vanished. It is vital at this point that you realize your bird is simply shaking its head like a wet dog, and is not headless in any way.

Reapply every 10 minutes or so, or until your emu gets bored.

WARNING!!! it takes a long time for an emu to get bored... with anything. A small piece of lint, dirt or even a Wednesday can dazzle an emu into an almost coma-like state.

Your emu will dry automatically.

If you don't have an emu, you can either wait until one simply arrives to live with you, unannounced and uninvited, purchase one, or you can create a fake one using a sock filled with newspaper, an old towel, or anything else of similar awareness.*

*I love my emu.**

**Actually, I love the emu that kind of lives here when it feels like it. It's not really mine. It just visits when it wants to rest its head on somebody's shoulder for a bit, or when there are some kids around who have been instructed to keep peanuts in their pockets.

Aquaponics - Pump change

I put a new (to me) pump in the blue barrel system and put it on a $3.99 timer so that now it runs for 15 minutes out of every 90 minutes. A lot of people in aquaponics seem to do this. This is because it pumps so much more water than the other one did. I'm not sure how it will go when there is fish in because I'm not sure if that will be enough oxygenation. I'm not sure about some stuff sometimes. I also have an old aquarium air pump, so that might come into play to solve the lack of oxygenation issue.

It looks like the system is cycled and running steadily so its time to get some fish!

Aquaponics - Sump and pre-filter

We cut the sump and pre-filter. The sump is going to be the trickiest part of this aquaponics thing. Not because it should be, but because I have no idea what I'm doing when it comes to painting with rubber paint. Who would have guessed? The sump will be positioned 10 feet further back and down the hill a bit, so the top will be level with its current ground level.

The pre-filter will be roughly where it is now but raised up a bit, so the top is level with the fish tank. The fish tank is yet to be bought and will be positioned against the pre-filter to the right of it.

Aquaponics - New pump and powerhead

My old pump looks like this. Yes those opposing wire loops I added are in fact the new front bearing. This is the pump thats been running for the last 45 days in the small blue barrel test system.

I took delivery of the new pump and powerhead. This is for the second, larger aquaponics system. The pump is the big box and the powerhead is the small ball shaped thing on the top left.

The pump will shift 5000 litres per hour at zero head. That is to say if all you were using it for as a stirrer it would shift 5000 lph but if you want it to move water uphill, the amount of water it can move tapers off depending on how high you are trying to move it.

For some crazy reason not all pumps tell you how much they can pump at any given height. This one only tells you that it can pump to a maximum head of 5 metres. That means you will get 1 drop per hour at 5 metres . From what I'v read and seen, at 2.5 metres you can expect a bit less than half of its maximum output. So I'm hoping this one will pump around 2500 litres per hour at 2 meters head. It might turn out to be a bit more than 2 metres so I made sure there was plenty of excess. I hope. All I need is 1000 litres per hour so It shouldnt matter.

The pump is 150 watts but will only run for a few minutes every hour. The powerhead on the other hand will run all the time in the fish tank, but is only 12 watts even though it also moves 5000 litres per hour. The powerhead cant lift water at all and is there only for its ability to stir water to aid oxygenation. The powerhead's other function is to create a slight whirl pool which will make solid fish waste gravitate to the center. Once there it will be picked up by the overflow outlet. and piped to the pre-filter.

Aquaponics - Sequencing

An ideal aquaponics system has twice as much grow bed as fish tank. The problem is, once you have twice as much grow bed as fish tank, when the tide is out your fish tend be walking around slightly more than fish tend to enjoy. The grow beds takes so much of the water that the fish tank becomes uncomfortably low.

If you fill one grow bed, and then the other in turn you will remove less water from the fish tank at any one time as there will always be another garden bed draining water back into it. There are a few products you can buy to achieve this, but pictured here is my first attempt at in invention to make this occur. Basically its a sea-saw where water is diverted from one side to the other when a float raises to the point where the sea-saw tips, diverting water to the other side. The sea-saw's floats are set at just the right height so that it tips to the other side just before the auto-siphons trigger. The siphons are triggered by the other smaller flow (water flows are all constantly on, and are pictured here as the blue arrows pointing down from the top) I made one of these and it seemed reliable enough even though it looked a bit like it was made by Homer Simpson. 

I don't intend to use a sequencer in my system as I'm going to use CHIFT PIST (Constant height in fish tank, pump in sump tank) which means there will be plenty of water for everything. If space is a problem a sequencer may be the solution. Aquaponics often involves compromise when building a system, especially on a budget, so I thought I would post this just in case it is useful.

[edit from the future - There is some additional material on sequencers. Readers might find this newer version in a post titled  The Bullwinkle sequencer build of interest. It's a better design, and only costs around AU$15 to build with off the shelf PVC components]

Aquaponics - My second system

The new aquaponics system has started to take shape. We cut the first tank in half and it will become the grow beds.

Two 1750 mm x 1100 mm x 300 mm grow beds to start with and we may add another later. Two grow beds this size will feed my partner and me with all the veggies we will need but she's keen to try a cut flower garden as well, as am I. We have decided on pumps, sumps and plumbing  that should allow for some expansion.

I think we will need to brace the middle sections of the grow beds with some wire stretching from the center of one side to the center of the other to stop it bulging. Each bed will hold half a ton of scoria so there will be some pressure on the longest sides. Once cut, the tank halves lost a bit of their structural integrity, this was to be expected and should be easy enough to fix.

We are still struggling with the decision regarding painting with gripset51 or using a pond liner. I think at the moment we are leaning toward using pond liner simply because it will be faster and there wont be any drying time. And I hate the smell of paint. I also just get the feeling that even though its plastic the pond liner will suit aquaponics a bit better than paint.

Just in case anyone cares, from what I can work out a ton of scoria is roughly 1000 litres in volume (as bought in 25 kb bags from the hardware), and a ton of  7 - 14mm blue metal gravel is roughly 670 litres

A thousand litres of scoria bought in bulk will cost around AU$145 and a thousand litres of blue metal road gravel will cost around AU$90

Aquaponics - Water testing

Its extremely important to make sure your water quality is within a desirable range. Aquaponics is remarkably stable and robust, but, for the first few weeks of setting up a new system it can require a little extra care. The best way to avoid any problems is to test your water every day until your system is mature and in balance or "cycled". (pictured here taking 30 days or so)

An aquaponics system is said to be cycled when it can process approximately 1 ppm of ammonia into nitrites and then process those nitrites into nitrates within 24 hours.

A decent freshwater test kit will enable you to get accurate test results for pH, ammonia, nitrites, and nitrates. It will set you back around 50 Australian dollars. They are widely available online or any good aquarium shop should sell them.

If you try aquaponics without water testing you will lose fish unless you are very lucky.

Add ammonia until you see a reading of 2ppm, then wait until your tests show ammonia is 0. Then add more and continue until your system can process 1ppm of ammonia and nitrites in 24 hours. Once you see readings of 0 ammonia and 0 nitrites you are cycled and can add fish.

Plants can be added on the day you first build your system but there wont be much for them to live on for a few days. My house water supply is rainwater and has some nitrates in it from normal environmental nutrient. Even normal tap water will have some nitrates in it so there will actually be something for small seedlings to live on.

Be careful to wash the soil from any store bought seedlings you transplant as they may have any number of additives that may be toxic to an aquaponics system. Growing directly in the grow beds from seeds is safest (and often quicker!)

Conduct water testing every day until you are cycled and then test every week or so or if ever anything strange occurs. Plants yellowing or dying can be a sign of something being wrong with your water chemistry and you might need to intervene in the early stages of your aquaponics system setup. More on correcting water problems later.

Always keep a record of your tests so that you can see emerging trends before they become an issue.

Aquaponics - Fish-less cycling

In order to create a backyard ecosystem we need to establish the nitrogen cycle. The nitrogen cycle turns fish waste into plant food, but perhaps more importantly it turns toxic fish waste into relatively harmless fish waste.

Having no photo that relates to this in any way I'll simply do what all media does these days and use some file footage. So here's a fish I prepared earlier.

The aim in fish-less cycling is to introduce ammonia in some form so that the bacteria that convert ammonia into nitrites can breed up and do their thing. Once nitrites are present, the bacteria that convert nitrites to nitrates multiply. This process can take a while as compared to some other beasties they are slow to reproduce (up to 20 hours to double in population).

Ammonia can be sourced by adding urea (bought in packet form from your hardware store or garden supply store) or by having a healthy, drug/medication free person pee in your fish tank. Within the online forums this second method is referred to as adding humonia or sometimes as peeponics.

In order to set the amount of ammonia correctly you will need a test kit. More on testing your aquaponics system later.

Aquaponics -Oops!

A few days ago I got some strawberry runners and, having no home for them, decided to make a small grow bed that would hang into the fish tank. When the main grow bed was flooded the water level in the fish tank would be below the new pot. When the main grow bed drained, the fish tank water level would be full to the top so the new grow bed would be flooded. No real problems there, in fact I felt a bit clever.

 I filled the pot with blue metal (road gravel in this part of the world) collected from my back yard. The day after I did this my pH went from 7.6 to 6. Now, I was told to expect a pH drop at this stage of fish-less cycling, and with the new gravel going in I thought it was within expectations.

The problem with pH readings of  7.6 or 6 is that they are at each end of the scale and as such it impossible to tell if they are actually beyond those levels. More on water testing aquaponics systems later.

Yesterday I discovered a white powdery substance near where I collected my gravel. I had a better look at it and discovered the gravel was dissolving! It was near where my flashing battery tail light for my mountain bike had rusted out so the conclusion I choose to leap to is battery acid!

I spent the afternoon washing out the system a few times, and now the pH is sitting at 6.8.

I was just a few days away from adding my fish so I guess its a good lesson to learn at this stage.

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