How useful are EC measurements in an Aquaponics system? Treating sick fish?

Do I need to worry about EC measurements?

An EC meter (Electrical Conductivity) is a device that measures the electrical conductivity in the water and therefore is an indication, usually of salts in the system water.

EC Trunchen

Very useful EC measuring tool.

EC measures salts, or total dissolved solids (TDS)

Almost all Hydroponic solutions are salts and therefore accurate measurements in a HYDROPONIC system can be read by noting EC readings. Hydroponic nutrients can be added to a Hydroponic system very accurately by using an EC meter.
Not so in an Aquaponics system. Our nutrients are not salts, so EC readings are only a very, very broad measurement of nutrients in an Aquaponics system and should not be taken too seriously, except when they do get too high, you should ask yourself, "Is there salt in the system? And, "where is it coming from?" Common salt can build up over time from various sources such as the use of low quality fish feed, or if you live in an area where ocean winds can carry salt into your system.

Generally, we do not like too much salt in our freshwater Aquaponics systems because food plants do not do well in salty water. Most freshwater species of fish can tolerate salt very well so it is not a problem for the fish. It is the plants that one would be concerned about.

An EC reading is also very useful if you need to have sick fish treated with salt in a hospital tank or quarantine tank where you would add salt to the water to treat the fish. In that instance a very accurate measurement of the salt added can be made with an EC reading device. Using salt to treat sick fish is one of the few ways we can treat fish that we plan to eat someday. It is not too desirable to use veterinarian type medications on fish we plan to eat someday.

Fish on Trial.

What will be the verdict?

We have started a feed trial with Jade Perch. The idea behind the 12-month trial is to see just how well the Jade Parch will grow being fed anything they will eat that can come off the land rather than use fish feed pellets that contain ocean derived fish meal.
With a view toward long-term sustainability, I feel we need to discover and refine feeding methods that are not dependent on ocean fish stocks. Seems elementary, but I really want to see just how well it will or will not work.

Aquaponics policemen.

Aquaponics policemen.

Expectations: I believe we will get the fish through to the 12-month point in a healthy state, after all, Jade Perch in the wild eat plant material and algae etc. I imagine that we will see slower growth in the plant fed fish but I believe they will be very healthy.

Time will tell.

In my INDY 23 system I have 2 x IBC tanks that are all part of the same system. Same water same pump system etc. I feel it is an ideal setup to test two identical batches of fish that share the same conditions except fo the feed they get.
There are 65 Jades in each tank. The fish are supplied by Ausyfish at Childers.
They have been in the tanks for one month. The trial feeding started 1st March.
Weigh in on 1st April.

The batch of 130 fish were evenly divided as to size as near as we could. Very difficult when they are so small approx 10g each fish; so we started with 650g of fish density in each tank.

Tank "A" is been getting up to 50g of 2mm pellets per day.
The pellets are as below
Crude Analysis
Protein Min 35 %
Fat Max 10 %
Moisture Max 10%
Ash Max 11%
Ingredients =
Chilean Fishmeal, Wheatflour, Soybean Meal, Shrimp meal, Squid, Aquamix,

Tank "B" is getting a diet of lettuce, cooked carrot, cooked pumpkin, Kang kong leaves, honeydew melon, eggplant, cucumber. It is difficult to know just how much to give tank "B" every day but we are getting better at keeping the feed up to them.

This is a piece of eggplant that they demolished overnight.

This is a piece of eggplant that they demolished overnight.

First weigh in on 1st April.
Sample of 20 randomly caught fish from each tank gave the following results.
The fish were weighed as a batch.

Group "A" = 30g
Group "B" = 23g

Group "B" have not put on much weight at all; 3g over 20 fish. So we need to up their feed somewhat.


This is the lettuce when they have stripped it of the green leaves.

This is the lettuce when they have stripped it of the green leaves.

Is the Pipe Poisonous?

Is the Pipe Poisonous?

Many ask the question about PVC pipe, should I use it in my home or commercial project.
Most folk use PVC mostly because at this time there is not much else readily available. Some folk really worry about PVC. There is a load of info out there on this kind of subject but, we need to remember, "the road to better, purer food is a journey, not a destination" In other words, we need to use the best materials that are available to us today. Don't stop the journey because of a small difficulty. It is far, far better to go ahead and produce clean carefully grown food. Keep moving forward on the journey.

Aquaponics pipe.

PVC Pipe is readily available almost anywhere.

The plasticizers in PVC that some worry about, and in other types of plastics need to be fairly warm before they start to gas off. Additionally, the inside of the pipe work will be very quickly coated with a layer of biofilm thereby effectively sealing off the PVC from direct contact with the system water.  I realise this is an emotive issue with some folk but we need to achieve a balance and use the very best materials we can secure for our project.  Some folk who will just not use PVC because of the perceived problems still commute to work in their plastic car, ride in plastic lined aircraft, work in a plastic office, sit on chairs filled with very dangerous plastics and so on.  In short, we are surrounded by plastic of one kind or another. The exposure of the Aquaponics system water to any danger, real or otherwise is so small by comparison to other plastic products.

Aquaponically grown produce is way, way better than anything on the supermarket shelf, even if we do have some materials to deal with that may be slightly less than our ideal.

The ideal material at this time is HDPE. There is plenty of HDPE pipe, but the fittings are extraordinarily expensive. HDPE pipe can be obtained at most irrigation supply stores. You will not usually find it in plumbing stores or hardware stores. HDPE stands for High-Density Poly Ethylene.  Poly Ethylene is said to be the only real food safe plastic material along with common old fibreglass made from properly cured polyester resin.

So, the important thing to do is get started, be prepared to use better materials when they become available, but....get on the road to better, more sustainable, nutritionally dense food for you and your loved ones.


Four levels of Knowledge –

Four levels of Knowledge -

Training class in progress. Practical hands on training.

A training class in progress. Practical hands on training.

The 4 day Master Class is a good mix of both introductory subjects and leading into and concentrating on commercial Aquaponics subjects. We have excellent material to share including some very extensive spreadsheets that will play well for your business plan development.

As you are most likely aware we have excellent credibility in this area. We have been delivering Master Classes in the USA and  Australia for more than 5 years. We are very fortunate having travelled around the world and consulted on many farm projects. Many of our students are running their own projects and some are building farms for others. Some are teaching and sharing with others as well as running their own Aquaponics farm.

Additionally, We are the holders of Australian Federal Gov approved 10427NAT - Certificate III in Aquaponics Organic Food Production. The only such course in the world at this time.  We are still finalising the teaching notes and training some staff to deliver this Cert III course.  We anticipate the first delivery of this course to commence in the first half of 2018.

So, we deliver Aquaponics knowledge in three levels;

1. Discover Aquaponics.  A one day course crafted, especially for the hobbyist. This gives a really good framework for the person wishing to grow their own chemical free healthy vegetables (and fish, don't forget the fish!) Dates to be announced for 2018 soon.

Aquaponics Greens

Salad greens growing in a home Aquaponics system

2. Aquaponics Master Class. A 4-day training course aimed at those who may be wishing to develop a commercial business in Aquaponics farming.  This course is by far our most attended and enthusiastically recommended by graduating students.

(Yes, we have many Aquaponics home hobbyists who complete this level of training because they want to be really good at producing their own food and move closer to a sustainable lifestyle.)
To secure your place in the Aquaponics Master Class, go here

3. Aquaponics Design Course.  This course is completely online. If you have an internet connection you can complete this course. This course has been undertaken by students from 40+ countries.
Over 100 videos in this course. The course now runs for 8 weeks,
Go here to read about this course.

4. 10427NAT - Certificate III in Aquaponics Organic Food Production. This is a 500 hour plus course that is designed to fit the student with in-depth knowledge of Aquaponics Farming.  This will produce qualified persons who can confidently enter into an Aquaponics farming venture. Further, it will produce qualified persons who an Aquaponics farmer can confidently hire as excellent, knowledgeable AP farm technicians.
This course will run for the first time in the first half of 2018.

Aquaponics Salad Greens

Aquaponics Salad Greens.  A farm built in the Middle East by one of our star students.


The Cost of Commercial Aquaponics.

Is it possible to build your own small scale commercial aquaponics system without costing you an arm and a leg? How much should it cost to build it yourself? How much money can you expect to earn? Where do you sell your produce? Where do you go to learn more about all this stuff?

Aquaponics Farm

Aquaponics Farm.

We grab hold of Aquaponics kit builder and teacher Murray Hallam and get the low down on his training course and how much money a small DIY commercial Aquaponics system would cost you to set up. His answers may surprise you.

Harvesting lettuce in an Aquaponics Farm. Practical Aquaponics.

Harvesting assorted greens for a custom order in an Aquaponics farm.

Transcript of interview.  Edited and updated 25 Jan 2015

Ecofilms: Now you’re running a course about commercial Aquaponics. Tells all about the motivation behind it because you were doing workshops last year in backyard systems. Is this the new hot thing?

Murray Hallam: Well it certainly seems to be from our perspective because we get phone calls literally every day from people who are wanting to go into commercial Aquaponics.

Now the definition of what is commercial is quite elastic as you can imagine for some people. Probably the biggest group of people we talk to our people who are at retirement age or near retirement age, they discovered that their superannuation pension plan is not going to get as much income as they thought it would so they what about do something that will bring in a $500 or $1,000 a week and is not too stressful and they see aquaponics is a great way to go.

Of course behind all that is their desire to be able to produce good clean food. Food through security, food purity reasons. So that’s what motivates them. That’s what excites them about aquaponics and they want to learn to do at that level.

Then there is the next group of people who are actually into the idea of a sea-change or a tree-change as we call it. They want to move to the country. They want to change their lifestyle. They’re sick and tired of living in the city and they want to do something they see as sustainable. It's a good thing to do that is going to provide good food and they can make a nice living out of it. That's the next group of people and once again that’s not a massive great big farm.

Then you’ve got another group of people which is very small, who see it as a way to build a mega-farm.

I personally don’t think that’s the way Aquaponics will succeed.  I think it’s going to be small family farms. Small suburban farms. Local food distributed locally. Cut down food miles. Food purity. Food security. They are all good reasons to do Aquaponics.

Aquaponics ticks all the boxes in those areas. Aquaponics commercially.

This 3,000 square foot system can be expanded to cope with local demand for fresh aquaponically grown lettuce.

This 3,000 square foot system can be expanded to cope with local demand for fresh Aquaponically grown lettuce and greens.

Ecofilms:  Because a lot of people when you say commercial aquaponics immediately think of enormous farms. Some of the large hydroponic farms and so on. Is there a limit to how big you can go commercially with aquaponics in your view?

Murray Hallam: I don’t think there is a limit.  I think that anything is done on a hydroponic farm scale could also be done aquaponically.  One might ask why would you want to do it aquaponically when it already is proven to do it hydroponically?

Well the simple answer is aquaponics is an ecosystem. By combining the two disciplines of aquaculture and hydroponics the third brand-new discipline all of its own called aquaponics has evolved and the beautiful thing about it is – what makes it distinctly different from those of the two is that it is an ecosystem. It relies on natural processes in order to produce the nutrient for the plants, in order to keep the fish healthy and plants happy. You produce two products (fish and plants) out of the same system.

It's very efficient and I see no reason why one day we will see great big farms. But personally I think the way the world is going – food miles need to be cut down. So it is no longer going to be economical to grow plants in one part of the country and transport them thousands of miles to somewhere else for sale. People are going to have to be to produce food locally much more locally. They are going t demand it to be delivered to them in a much fresher state. In a much purer state.  Aquaponics ticks all the boxes.

Ecofilms: So you are about to embark on a course teaching commercial aquaponics in Australia as well is in the US states in March and July of this year. (2015)  Can you tell us a little bit about what people will learn, will discover in that course? Will it be just a course to introduce them to that? Or will they be able to go home and have enough material in their hand to embark on a project?

Murray Hallam:  Yes the training course we’re doing in Brisbane starting 2nd March will actually have hands-on building of troughs and fish tanks to show people exactly how to do it so that people can go away and build it themselves or employ a contractor and know exactly what the contractor ought to be doing so they get the result they want. They will also have training in our legal requirements. What are the legal requirements at the moment in Australia for running an Aquaponics farm?  We will touch on business marketing. All that kind of thing because really the key to making it successful is being able to sell the product, because if you can’t sell the product at a good price then the whole thing goes up in smoke. So we’ll have a lot of discussions about how to sell the product. How to gain a premium price of your premium product and then of course will be the theory of the whole thing. How does Aquaponics work? How does that bacteria convert the material? How does it make it all work?

People need to understand that and that's a general outline of what will be covered in a very broad way.

Ecofilms: What would be the upfront costs for someone who wanted to set up a small commercial Aquaponics system? Say they had are some acreage and wanted to perhaps sell (produce) off the road or go to a farmers market. What would their costs be to run something that could earn them $500 to $1000 a week?

Murray Hallam: Well at that level, if you going to build it all yourself and do it all yourself you could build it for a minimum of say, $20,000.  That’s my guess. Buying new materials and providing all your own labour and buying a decent greenhouse or greenhouse materials and that kind of thing. Once again that depends on where you live in the world. For example here in south-east Queensland where we enjoy a fairly good climate all year round, it’s cheaper to build here obviously than it would be in one of the northern states of the USA where they have really cold winters and they might require heating in the winter.

So that would add additional cost for what they do. Or in the southern states of Australia for example right down in Tasmania and Victoria, your building costs will be different there than what it will be in a place like south-east Queensland or for example in Texas or Florida USA.

So those figures at pretty hard to be definite about but you’d be looking around about $20,000. If you wanted to get someone to come and build that for you, that same kind of thing, as a turnkey option, it might cost you $50,000 to $100,000.00. It's a very difficult thing to put a price on it, I have to be honest, without proper assessment of the particular project.

Ecofilms: It would be a floating a floating raft, deep water cultures system?

Murray Hallam:  That would be a part of it. We have what we call our FloMedia system which is a combination of both floating raft technology and also media bed technology and one of two other little things began to throw in the people really enjoy finding out about when the course runs, that will help you grow all sorts of things in your systems and grow very well and make sure that you utilize every little bit of that beautiful natural ecosystem nutrient that is produced by the system. That’s very important I think. To get a good cross-section of all the different crops that you can grow and grow in your local area. We’ve had some experience with some farmers now in the USA particularly, that are told us that they can sell all they can grow but the difficulty they have is that the customers want more than just lettuce or just tomatoes or just carrots.

They want to be able to buy a variety of things that are grown in the Aquaponics system. So it has become very obvious to me that we need to be able to produce a whole lot of variety of quality vegetables if we’re going to successfully sell locally and produce and run a truly local business.

Ecofilms: So just getting back to FlowMedia at this is the a lot of interest in what it is exactly because it’s a combination as I understand it of floating raft and gravel media systems so that you can run different sorts of crops. Is it two systems split or are they somehow joined together and work off one pump?

Murray Hallam: No they are joined together and work with one pump. We spent quite a long time working out the parameters of how to do the plumbing so that the water distribution is done correctly and that the nutrient distribution is done correctly so that everything works really nicely in one harmonious system and can be run of just one very small low wattage pump.

That is the key to the whole thing. Keeps a running cost right down, but make sure we have maximum efficiency running through the whole system.

Ecofilms: And will you be teaching people FlowMedia in your Courses?

Murray Hallam: Absolutely yes.

Ecofilms: So this is something that really nobody has cracked yet. Would that be right to say?

Well, there are lots of people that are dabbling in it right now. There’s a lot of interest around. Just fascinates me. We’ve been playing around with it for more than five years and working out – making sure we know exactly how it should and shouldn’t work and just in the last 18 - 24 months, I guess, there’s been an explosion of interest in what some are terming hybrid systems because people are beginning to realize that to take all the nutrient out, to take all the waste material out, the fish poo, take it out of the system and basically discarding it, it’s not very smart.

Because there’s a whole lot of great nutrient and minerals locked up in that fish poop. To take it out and throw it away is pretty silly – which is what happens in a typical floating raft system. It’s taken away. Some people are a bit more clever, will treat it and try reintroduced nutrients back into the system but that is another job you have to do. Another process you have to do.  Whereas the way we do FlowMedia is it’s all done in the system and there’s no waste and the nutrients are retained in the system and the system just works absolutely beautifully.

Ecofilms: Tell us about your Australian Course. When is that happening and how long is it run for?

Murray Hallam: Our Australian course will happen on the 2nd March through to the fifth, 2015. It's four days and it’s pretty intensive actually. We’re going to have a difficult job keeping it down to four days. I reckon we could do six days really. But four days is what it is, and we going to cover all subjects we talked about earlier. The ones we’re doing in the USA in Oregon and Texas in July we actually are going to run two sessions.  Two identical four-day sessions because we’re anticipating the number of bookings will be quite high

Ecofilms: Well thank you Murray I think the fact that you’ve given us that little tip about how much people can spend on building their own small-scale commercial aquaponics system is a tremendous incentive. I think most people can find that sum of money if they were close to retirement age. I’ve always thought one of the beauties of Aquaponics is that all the food is almost at waist level. I always like the fact that I don’t have to bend over and pick things and it’s just an easy stroll. I feel lazy saying that, but it’s one of the advantages I think.

Murray Hallam: Well is another little advantage that comes with that as well. We’ve noticed that food is grown at waist height has a much lower pest problem than food grown on the ground, believe it or not. Now I’m not quite sure why that is, but it’s a much cleaner food, much better food and it’s just fun to work with.

Just backtracking a little bit to the cost of doing an Aquaponics system, we must stress that that’s assuming you already have some land and you already would have a place to do it in. If you have to go and buy land then obviously it’s a whole different kettle of fish. (no pun intended)

Ecofilms: When it comes to selling your produce as a general rule what should people be focused on? What advice would you tell most people who are considering doing a commercial Aquaponics course?

Murray Hallam: The first thing we say to people who contact us, the first thing you need to do is work out where and how you’re going to sell your produce. It’s not good enough to say, “Oh, Uncle Fred has a fruit and vegetable shop and he said he’ll buy it from me.”

You’ll probably find Uncle Fred won’t when the crunch comes.

You can’t go into this with just some loose idea that because you’ve grown a better product that people rush to your door and buy it. They may not necessarily. You have to have a good plan which we can help you formulate that plan in these courses. We will help you formulate that plan. Something will work for you in your area and you really need to sort that out long before you start worrying about how big the greenhouse is going to be or how big the pumps going to be. Those are all easy things to solve.

The big issue is where and how am I going to sell it, because this is a premium product and you must obtain for it a premium price. If you’re just going to send it off to a local bulk wholesale place you’ll get very poor prices and you won’t make a living.

Further Information

Murray will present his Australian Aquaponics Master Class in March 2-5, 2015 in Brisbane Australia.  See course outline here.

NB, please check the links above for current dates and times.

This article edited and updated January 25, 2015.



Plants With Wet Feet.

Aquaponics Ripe pawpaws on tree

An Aquaponics Papaya or Pawpaw tree heavily laden with fruit.

Plants with wet feet

I want to be able to grow fruit trees as well vegetables.  As you can see, I am having wonderful success with the Paw Paw (papaya) trees.

Aquaponics pawpaw.

Look at these beauties. Yes...grown in Aquaponics media beds 300mm (1') deep.

I’ve got a good friend who is a retired Paw Paw (papaya) grower from way up in North Queensland and he came and told me that we simply could not grow Paw Paws (papaya) in this environment because, evidently, Paw Paws (papaya) don’t like wet feet.

Have you heard that expression, “you can’t grow that plant in those conditions as it doesn’t like wet feet”?

It would be more correct to say that the plant does not like lack of oxygen around its roots!

If we are running a flood and drain system, where we flood the bed and then drain the bed, we flood the bed, we drain the bed, over and over, continuously.

What we are actually doing is delivering water and nutrients every time we flood the bed, and loads of fresh oxygen is being delivered every time we  drain the bed.  The plants that just should not grow in a very moist environment actually grow extremely well, why?  Because they are getting all the nutrients that they want, all the water they want, and they are actually getting all the oxygen they want around their roots.  That’s how we have been able to grow Paw Paws (papaya) so successfully.


Aquaponics System Biology…1

SCOPE: To discover the important parameters and better understand the role of natural processes in an Aquaponic System.

Aquaponics System Biology…1

We understand that in Aquaponics system produces fish and plants together in one symbiotic system, and we now know that there are two major bacteria that convert the primary waste of the fish, Ammonia to Nitrates, that is, plant food.

Just to recap on those two Bacteria families are …
1. Nitrosomonas bacteria
2. Nitrobacter bacteria
Bacteria of various types is all around us and in our own bodies. There are simply millions of different bacteria. In nature bacteria perform many complex tasks taking one compound and by extracting energy from it for themselves convert it to another compound. These two bacteria groups listed above are particularly important to our needs and given the right conditions will work for us around the clock.

Bacteria needs a food source, water, and be housed within a temperature and pH range conducive to their happy survival.


  • The temperature for optimum growth of nitrifying bacteria is between 77-86° F (25-30°C).
  • Growth rate is decreased by 50% at 64° F (18° C).
  • Growth rate is decreased by 75% at 46-50° F. (8 to 10 C)
  • No activity will occur at 39° F (4° C)
  • Nitrifying bacteria will die at 32° F (0° C).
  • Nitrifying bacteria will die at 120° F (49° C)  (1)

Nitrobacter bacteria is less tolerant of low temperatures than Nitrosomonas bacteria. In Aquaponics systems, care must be taken to monitor the accumulation of nitrites especially when there is a change in water temperature of the system.

pH range.

  • The optimum pH range for Nitrosomonas is between 7.8-8.0.
  • The optimum pH range for Nitrobacter is between 7.3-7.5

Nitrobacter will grow more slowly at the high pH levels . At high pH Nitrosomonas will grow more slowly and increases in ammonia may become evident. On the low end Nitrosomonas growth is inhibited at a pH of 6.5. All nitrification is inhibited if the pH drops to 6.0 or less.

Care must be taken to monitor ammonia if the pH begins to drop close to 6.5 as it may not be being processed as quickly as it is at higher pH levels.
This information has been taken from standard texts on the subject and we have observed that the tolerance range is most likely wider than most texts suggest. (2)

Beneficial Bacteria have four main benefits for areas like fish intestine lining and plant root tissue.

  • Beneficial bacteria help the balance of a system by: (Fungi help as well but that is another discussion)
  • Preventing harmful bacteria from taking hold. If the system is already occupied by a beneficial bacteria then the harmful bacteria has difficulty in taking hold. The microbes make Aquaculture and Aquaponics possible.
  • Promoting system health. Beneficial bacteria play an integral part in breakdown of organic material and actively assist plant and fish tissue health.
  • Being antagonistic to harmful bacteria. Beneficial bacteria inhibit harmful bacteria taking hold. By actively antagonising harmful bacteria the harmful bacteria are held in check in the Aquaponics system.
  • Improving nutrient uptake and general system health.

Aquaponics Microbes:-
It is most important to understand that many more things other than just the two bacteria groups discussed above. Many more are at work in the natural ECO system that we have pulled together in building an Aquaponics system. Fungi, algae, zooplankton, phytoplankton, protozoa, nematodes, just to list some. All of these microbes are the “work horses” of the system. Bacteria process the fish wastes into products that are non-toxic to the fish and make these products available to the plants as food.

Learn more about the actual numbers and parameters by attending the Practical Aquaponics Master Class

(1) Nitrifying Bacteria Facts - Bio-Con Labs. (n.d.).
Retrieved from

(2) Bhaskar Vijaya , E?ect of environmental factors on nitrifying bacteria isolated from the rhizosphere of Setaria italica : Department of Microbiology, Sri Krishnadevaraya University, Anantapur 515003, AP, India. 2005.


Jade Perch, Tilapia and Lettuce…Common Requirements.

Keeping fish and plants together has some basic requirements and important parameters.

Digital thermometer in an Aquaponics system used to switch electric heaters on and off in a 2 degree range. Temp shown is centigrade.

Digital thermometer in an Aquaponics system used to switch electric heaters on and off in a 2 degree range. Temp shown is centigrade.

Water temperature is a very important parameter. If the water temperature gets too high it will knock the plant performance back. The ideal temp for both plants, Jade Perch and Tilapia is 23C ( 73F) as it goes higher or lower the performance of both plants and fish drops off.  Tilapia will still be fine in water up to 30C (86F) and a little way beyond.  Plants will also survive but do much less well, particularly lettuce and the like.

The system water temps do not necessarily follow exactly the outside air temp although they will gradually trend upwards in a succession of hot days. We see weeks of 33 -35C (90 - 95F) here in our South Queensland summer, our nights are usually average around 21C (70F) so over the summer the water temp gradually climbs to level out around 28 - 30C (83 - 86F) Not so bad. Everything works just fine in that temperature range.

The system water in our Aquaponics garden is the nutrient and dissolved oxygen transport vehicle as well as providing moisture for the plants and fish.  In a well designed Aquaponics garden nutrient and dissolved oxygen are continuously moved around and made available throughout the Aquaponics system.  Obviously both plants and fish will do much better when both dissolved oxygen and temperature are at or close to ideal levels.

This last summer we had one week of temps above 40C (104F) with one Saturday to 46C (115F) which was just an unbelievable day.

Hot mate, you could fry an egg on the footpath!

Fried egg.

That day my water temps got to 34C ( 95F) and I lost a number of fish. All big guys too which was very upsetting. I was away for the day so could not do anything about it till I got home just before dark to find fish gasping at the surface and a number of dead fish.

Above 30C (86F) the ability of the water to hold dissolved oxygen drops off rapidly so, result equals fish deaths and plant destruction. Water will only hold half the saturation of oxygen at 30C (86F) that can be held at 0C (32F).

Interestingly, if you can maintain reasonable root zone temps the plants may wilt a bit during a very hot day but will recover rapidly once the evening comes and will still grow and bear fruit in the case of tomatoes and cucumber for example.

So....root zone temperature control is the holy grail of delivering excellent results in your Aquaponics system.

Temperature control is equally important in cold climates, winter conditions.  Depending on where you are in the world this can be challenging or not so bad.   We will deal with that in another post.

I hope this is helpful to you.


Aquaponics Water Supply – Municipal or Town Water – Tech Tip.

Top up water for your Aquaponics system can come from several sources.

In this Tech Tip we will discuss Town or Municipal water.

Aquaponics water tower Aquaponics

Municipal Water Supply contains all sorts of chemicals.

Town or Municipal water should not need testing. Chemical analysis of your local municipal water is usually obtainable from your municipal water supply authority.  A phone call to your water authority will often be enough for you to discover the important parameters.

Municipal water will contain chlorine or chloramine. These are added to kill bacteria and other living organisms, including fish, that may be present in the water supply.

Chlorine is easily gassed off by putting it into a holding tank, applying vigorous aeration for 24 hours.

Chloramine (NH2Cl) is commonly used in municipal water as an alternative to chlorine.  Chloramine is much more stable and does not dissipate as rapidly as free chlorine. Chloramine is formed by ammonia and chlorine being combined. Some chloramines could readily form in Aquaponics system water if you were to add chlorinated water straight from the tap to an Aquaponics system tank that already carried some free ammonia. If you cannot get a report from your water authority and you strongly suspect the presence of chloramines, obtain a test kit that is able to test for "total chlorine" or "combined chlorine," not for "free chlorine." A test for "free chlorine" would misleadingly read zero in chloraminated water.  ( 2014)

Chloramines can be removed from your source water by,

  • Boiling and degassing. (not very practical for large quantities)
  • Ultraviolet light. (Well established method of removal). (Adelstein, B 2013)
  • Activated carbon filter. (pass the water through slowly)
  • Commercially available de-chloramination products (some simply remove the chlorine, while others 'lock up' or detoxify remaining ammonia) ( 2014)

It is best to treat any suspect water in a holding tank before using for top up in the Aquaponics system proper.

More Teck Tips on water supply in following blogs.

See our training courses Here

AP Tech Talk – Lousy Pump Performance.

Aquaponic Pump Teck Talk.

Pump failure can lead to fish deaths, and bad case of pump hate!

Many make lousy decisions on choosing a pump for their Aquaponics system.  This is most evident in some DIY home system builders.  While trying to save a buck or two it costs more in the end.  Mind, I have seen commercial farm projects running on some pretty poor pump installations.

It is best to oversize the pump in any case on any system in my experience, both in home and commercial systems.
Excess pumping capacity is always useful, to cope with expansion of the system (happens very often) or to redirect water back to fish tank for spray bars and the like. The list can go on. The little extra cost in electricity is more than compensated by the improvement in performance of the system. A robust system will return you much more value in produce and fish.

If you wish to focus on economy of operation it is wise to consider the following.

Practical Aquaponics Pump

A Mid range Italian made 4000 lph pump. Very suitable for home AP systems.

1… Buy a better quality pump. Better quality pumps are much more reliable, run more quietly and most often have good warranty and parts backup. The cheap pumps from “oogy boogy” land will work for a while but it is just plain unreliable to go that way.  The lower cost pumps often consume many more “watts” that a better manufactured pump to move the same amount of water.

2…Make sure you do a good job of the plumbing.  Correct size piping with sweeping bends and as few bends as possible makes for less pipe friction and better performance. Generally speaking, the size (diameter) of the pipe used to transport your water around the system should be at a minimum the same size (diameter) as the actual outlet on the pump itself.

Extra pumping capacity delivers better water control, more flexibility in design and layout. CHOP1 is just fine and so is CHOP2. All of our systems, except the very small run on CHOP2.  Even our FloMedia research system. (1000 holes of raft + 11 mtrs of gravel beds, swirl filter) runs very well using CHOP2 on a 7000 lph pump which has enough excess capacity to run another 1000 holes of raft beds.

Pump examples shown below compare pumps of different capacity. 4000 lph (1000 gph) and 6000 lph (1500 gph) for larger home systems and a 2000 (500 gph) lph as a minimum capacity pump.

Based on 22 cents per kilowatt hour cost. Check how much you are charged per kilowatt hour for mains power in your area and do the comparison.  These figures come from pumps we have actually run at our facility.

Cost to run a 4000 lph (1000 gph) cheap pump per annum = 192.00 per annum
Cost to run a 6000 lph ( 1500 gph) cheap pump per annum = 376.00 per annum
Cost to run a mid range quality 4000 lph pump per annum = 115.00 per annum
Cost to run a mid range quality 6000 lph pump per annum = 269.00 per annum

Cost to run a 2000 lph (500 gph) cheap pump per annum = 105.00
Cost to run a 2000 lph (500 gph) good quality German made pump = 67.40

It is easy to get hung up on electricity costs. Heaven knows we are being slugged and ripped off like never before, but it is the old cost -v- benefit thing. Pay a bit more to run the right pump to deliver a good outcome and the benefits more than outweigh the small additional buy price and running cost.

Pumps and other pumping issues are discussed in detail at my Aquaponics courses
Choose a course that suits your location and time frame.  Courses running in Brisbane Australia, California and Florida.

Murray Hallam Practical Aquaponics

Murray Hallam ..A Food Freedom Rebel. Aquaponics....A pure, secure food system.

Murray Hallam.
Food Purity - Food Security.