Monthly Archives: January 2012

Murray Hallam



Murray Hallams Practical Aquaponics

Murray Hallam’s Practical Aquaponics.

Since coming across the Aquaponics Concept by a chance conversation, I have been totally hooked on Aquaponics.

I have always been very interested in
growing my own vegetables and a keen fisherman, so the idea of
Aquaponics (being able to grow your own fish and vegetables together)
really struck a chord with me.

On searching the net and other sources I
discovered that there was very little product available that truly
suited the needs of a Backyard or Commercial Aquaponic project. I was
not able to purchase decent Grow Beds and Fish Tanks or pump equipment
that was suitable for the task.

With my experience as a boat builder, and
skills in Fiber Glass I decided early to manufacture the right Grow
Beds and Fish Tanks for my own use and other Aquaponist’s in Australia.

Some time after that initial conversation
I contacted Joel Malcolm in Perth, purchased his book “Backyard
Aquaponics”, which proved to be very useful.

At that time there was very little information about Aquaponics available on the Internet or in book form.
I started right away to get some Australian native fish and get on with
learning all I could about Aquaponics by practical application.

My approach to Aquaponics is a very
practical one, I actually have several Aquaponics systems operating at
all times producing vegetables and fresh fish for our table. During this
time I have discovered what works best and what doesn’t.

We have manufactured and sent hundreds of
our premium Aquaponics Kits to all corners of Australia and exported
Aquaponics kits to the USA, Bahamas, Hong Kong, China.

My Aquaponics DVD’s have been sold all over the world.

Our Company Name is –

Team Economics Pty Ltd abn 53087289745
21 – 31 Hives Road
North Maclean
Qld 4280
Phone 07 3200 0272
Fax 07 3297 5154

Trading as
Practical Aquaponics
Australian Aquaponics
Future Farms.


The full length, 90 minute DVD can be obtained from
Practical Aquaponics for Everyone.
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Dr Wilson Lennard





Dr Wilson Lennard

Dr Wilson Lennard is an Australian scientist with a PhD in Applied Biology. He has studied and installed commercial aquaponics systems around the world. In this extended interview, over the coming days, Dr Lennard will discuss the state of play in Aquaponics research today, as well as his views on how to successfully run a backyard system, a commercial system, his new fish sizing calculator, the alarming flood of “aqua-shysters” as he calls them or marketers that are jumping on the Aquaponics bandwagon and what’s in store for the future of Aquaponics on the planet.

In general terms, what are your scientific qualifications?

I have a BSc (Bachelor Degree In Applied Science – RMIT Uni 1990), an Honours Degree in Applied Biology (Aquaculture manipulation of yabby reproduction – invitro fertilisation, egg raising and semen extraction from the Australian Yabby – 1992 RMIT Uni) and my PhD in Applied Biology (Commercial optimization of aquaponic systems with relation to adaptation to Australian conditions and fish species – 2006 RMIT.




How did you first get interested in Aquaponics?

I first became aware of aquaponics in the mid 80′s when my interest in aquaculture started. However, other things like Uni etc…got in the way and i didn’t go back to it until 2000 when I was working and decided I wanted to do my own aquaculture research.

It was then that i became aware of Jim Rakocy and his work and I did about 12 – 18 months research (literature work) and then wrote a $300,000 research grant proposal to RIRDC (Rural Industries Research and Development Corporation – federal government). I was unsuccessful with the grant application but RIRDC offered me a PhD scholarship, which they give 3 per year for the whole of Australia, so i think they were interested and I was very lucky!


Some people say Aquaponics is just a recirculated Aquaculture system with a Hydroponics component tacked on. Is this how you view Aquaponics?

My initial interest was from treating aquaculture waste, so yes, initially I saw aquaponics that way. However, over time, working with systems and seeing how they operate etc…I have discovered that they can be much more. However, I think it really depends on the hydroponic component and how that is designed. Some hydroponic approaches help build a more complex ecosystem than others. I would say that media bed systems have the highest ability to be an ecosystem, because media appears to assist the range and number of micro-organisms a system can support. Media also helps provide a higher number of niches for the bugs to fill. The next is deep flow and the last is NFT; I have an NFT system in NZ and it has proven more difficult than any other system and it behaves more like a traditional hydroponic system than an aquaponics system. i would now only advise NFT as an add on to an existing system which can take the additional plant growing capacity; fully NFT aquaponics requires skill and because the water volume is so low it needs to be understood that an ecosystem doesn’t develop as efficiently as the other methods. NFT as a few channels added to an existing media or deep flow system is fine, as you have the ability of the deep flow or media already built in there to produce the ecosystem.

Who in your view are the main Aquaponic players in the global arena?

Well, I work solely in the commercial realm, with a large emphasis on science, so I can only comment on that. The main player, guru etc…was Jim Rakocy, and he still is, but he has retired and will now concentrate less on aquaponics as a whole. A true pioneer with 30 years aquaponic application – you cannot beat that! Another is Dr Nick Savidov from Canada. He has done some great research on aquaponics and is developing more sophisticated approaches to the hardware utilized in systems. There is also Carlos Leon in Mexico, who assists many people to build commercial-scale, UVI style systems in Mexico. There are now emerging a few other Uni’s around the world who are beginning aquaponic research, so they will come into the picture soon as well. For example, I know of several research groups (government and private) starting in the USA and others in Israel, The Netherlands, Iran, Hawaii and South America. There are also several groups who have been around for some time and looked into aquaponics in the past and have now come out of the wood work now aquaponics has a larger public profile, which is fair enough. Rebecca Nelson and John Pade in the USA are also prominent in the USA and are expanding around the globe and have done great work spreading the word. There are others out there who say they are experts etc…but I see little from them and some of them are basically ripping people off and telling a whole lot of lies in their own commercial interests; some are quite prominent and have their supporters, so maybe they know more than I do about them, but I am not convinced and just see “money making” as the main motivation. I measure my interest by the commercial and scientific sectors, which are still very young and in development.

Is Aquaponics research still ongoing and being studied? How much is still unknown?

As I said above, aquaponics research is starting to be taken up by other Uni’s etc..and new players are coming along. Many of them are repeating work already done, which is frustrating, but I guess required for them to learn. The UVI model has been around for 20 years, but no one seems to take the outcomes from that seminal research as a starting point and they all seem to want to do it all over again. I probably get around 10 papers per year to review for journals and many of those have nothing new or novel about the research and in fact, most of it seems retrograde at best with them making the same mistakes we all made in the past!! There is still plenty to learn, as for all science, and it never will end. I think the next frontier is for all to realize that you can actually run these systems more efficiently than they currently are. My approach uses a good percentage less than the fish required by any other commercial approach, and I think it could be improved still beyond that. The other frontier will be microbiology based, which will hold many interesting things and efficiencies for systems. This includes initial ID of the species inhabiting the systems, but then moves into how can we manipulate things so we get the bugs we want in greater numbers to do all the work for us. In addition, a lot of aquaculture feed research is now based on trying to replace animal proteins and fats with plant proteins and fats. When we have a fish feed that all fish will eat and doesn’t require wild caught fish to make it, that will be a revolution for aquaculture and aquaponics. I also think that will link in with us choosing vegetable eating species over carnivores and even culturing vegie eating fish just to produce feed pellets for carnivore fish. I think the future of aquaculture is this style of multi-level approach where we simply grow some fish on vegie diets so we can then grow the fish we like to eat by feeding the vegie eating fish to the carnivores.



There seems to be a unusual level of interest in people tinkering and building backyard aquaponics systems around the world. What do you make of all this?

From my limited experience with the backyard industry, I see two major users:

  • people who want a system simply to grow vegies for themselves (and a few fish)
  • people who are attracted to 1/ above, but are also attracted to the technology (the tinkerers)

This second group seems to contain the people who are more interested in the technology itself and strive for improvements in their home systems. I am sure there are people out there with a wealth of knowledge in making backyard systems work really well. Making something yourself is also the way I would do it as that is what interests me too; I just add in all the nerdy science stuff! I think it is good and provides a broad knowledge base and shows there are many ways to be successful with aquaponics.

I am also sure it is a lot of fun to tinker in your backyard on the improvements you wish to try on your aquaponic system. As I say, I essentially do the same thing, I just build bigger systems and include a bit more nerdy science so I can predict it all a bit more.

You’ve tested a number of kits systems from the two main Aquaponic kit manufacturers in Australia. In general, how did you find the quality and build?

I haven’t tested any kits at all. I have run some of the designs through my backyard design tool so i can predict and test what the best level of operation in terms of the required fish biomass is to meet the nutrient requirements of the attached media bed. I have used modified UVI fish feed input to growing area ratio’s for this. However, I should also state that my approach to commercial aquaponics uses far less fish feed per unit area than other approaches.

Many backyarders may agree with this, as they seem to use low fish feed input numbers as well and have success. So, the model was designed for newbies to aquaponics so they had some hard predictable numbers to work by so they would increase their chance of success. I have seen the build quality of some and it seems fine to me; it is pretty hard to stuff up tanks and plastic plumbing now a days really, so build quality should be good at an affordable price, which as i say, it appears to be.

What basic advice would you give newcomers to Aquaponics looking for sound practical advice?

My advice is simple to anyone; LEARN HOW TO LOOK AFTER FISH PROPERLY!  People seem to put little emphasis on fish as they really want the vegies grown. However, keeping fish correctly and good water quality maintenance and control is essential to basic aquaponic operation and leads to ease with growing plants. I knew little of hydroponic plant culture before I started my research, but had a lot of early success with the plants and I think that was because I have an aquaculture background and know how to look after fish correctly. I see too many backyard systems with fish in poor health, or not growing, or not eating etc…and this all is because basic fish husbandry isn’t understood. If you are going to keep fish then you have a responsibility to look after them the best you can; you are responsible for their quality of life, whether you end up eating them or not, so the only way to do that is to make sure you know what you are doing. Basics like pH and conductivity testing and buffering aren’t even done by many back-yarders who just say that “the fish are still alive, so all is fine” This is a lazy attitude I think and shows little care for the fish.

Once the fish are sorted out, the plants take care of themselves and generally require little effort. Basics are:

  • Test pH 4 times per week
  • Buffer the water back to the required pH using proper Potassium and Calcium buffers so plant nutrient requirements are met.

If you do this, there is also no need for things like Seasol or Maxicrop, as the plants will always get all they need. I am also aware that people are being told to add common salt to their systems to combat fish disease and parasites. If you look after the water correctly, fish rarely get sick and so salt isn’t required. If you need to add salt at ANY stage, there is a good chance you aren’t looking after your fish correctly and they are in bad health and therefore, susceptible to disease and parasites. People also get told to add shell grit or oyster shell to their grow beds to control pH. When I test the water, it is at pH=8 or above! If you add these to your media you have zero control over the outcomes, and again, i think this is a lazy approach. It isn’t required. I recently saw a system in Melbourne, very nice off the shelf job and I thought what a reasonable price for the set up. BUT, the owner added oyster shell (apparent forum advice) and couldn’t control the pH. Bad advice! I believe as he couldn’t control anything and was at the whim of the system as to how it performed.

I know it is hard, but don’t believe everything you are told or read. Its not always the best advice. The issue I think is that people at home try things and it works, so they post the outcomes and suddenly it becomes gospel, even though there is no scientific basis or support and it hasn’t been proven by anyone else. Not everything that works in one system will work for everyone else and it needs testing and verification before it is more widely adopted.

You advocate NOT using Seasol or Maxicrop (Seaweed Extract) in an Aquaponics System. Why is that?

Seasol or Maxicrop or any other complete, and especially sea-based plant suppliment shouldn’t be added to aquaponic systems for technical reasons (ie: Sodium salt build up which eventually kills plants), but also for philosophical reasons. I see too many backyard systems sold in Australia where people are told to add Seasol regularly. Sure, this makes for good plants initially, but can be a cause for eventual system crash and failure. Seasol has a very high sodium content (from the salt in the water). There is nothing in a freshwater aquaponcis system which requires anywhere near the sodium levels that occur when Seasol is added. In addition, if Seasol addition continues then this sodium just accumulates (the point of aquaponics is to not change any water, so if something isn’t used by fish or plant, it builds up and doesn’t stop building up) and this will eventually lead to plant loss and a lowered plant production rate as it affects plant metabolism and growth and nutrient uptake. Salt addition (as recommended by some) will do the same thing. The thing I like the least is that this Seasol/Maxicrop addition essentially also makes these systems effectively hydroponic systems with a few fish swimming around in them, with the plants ALL growing from the Seasol and the fish contributing zero to the plant growth. If you want to add this stuff, leave the fish out of it and accept it isn’t a true aquaponic system, but as I say, a hydroponic system with a few fish swimming in it. To back this up, i recently went to a system in Melbourne where the person was told to add Seasol once a week. There were not enough fish in the system to feed all the plants via fish waste and the person admitted that the fish weren’t even eating and were regularly dying, but apparently, this is still an aquaponic system? I will say it again, if you manage and maintain the system correctly and use a proper testing approach and a proper buffer pH control approach, there is zero need for Seasol or anything else at any stage in a system. The whole idea is to maximise the use of the fish waste for plant growth; adding Seasol just counteracts this and so removes the whole point of adding fish in the first place.



Why is there very little take up of Aquaponics in the commercial arena around the world? Is it lack of knowledge, too new and unknown or just too hard to make it work profitably?

Its not to do with making it work properly; it has been put to bed by now that this technology works and works well. My work at University and in New Zealand shows categorically that you can match, and even sometimes better, hydroponic plant growth rates and the harvest quality of the plants. Its more about whether it is financially viable or not. All commercial entities need to make money, that is one of the reasons why you do it!

There isn’t enough data available yet to demonstrate categorically that it is economically viable. Everyone is waiting for someone to prove this by risking their own cash. Once someone does it on a large scale and it is proven viable, there will be large “jump on the band wagon” approach.

This happens with all technologies, especially agricultural ones. Unfortunately, there has also been too many people who believe they are experts and build systems and then they fold because they cannot make money. The money comes from knowing business, not aquaponics! This is about business, not the technology. You can can grow as many lettuces as you want in an aquaponic system, but if you cannot sell them, have no market, cannot get the right price, it all falls apart. So, aquaponics is going through a start up phase and this will be the reality for some time until success is achieved financially for someone.

You say you only add three things to your commercial systems. Calcium, Potassium and fish waste and nothing else. Can you expand on that statement? What form of Calcium and Potassium do you use? Is that enough for plants to thrive? What about nutrient deficiencies?

I add calcium hydroxide (hydrated lime) and potassium carbonate to buffer the water back up to my desired pH of 6.8

The basic part of these salts (ie: the hydroxyl and the carbonate) buffer the water upwards. This is the primary requirement and also happens in fish only systems, where sodium bicarb is usually used as it used to be cheap and easy to find. However, sodium is no good for the aquaponic system, so we just swap it for the buffers I use (and everyone else uses) for buffers that carry an element (nutrient) the plants will uptake; hence the potassium and calcium. My systems use small doses of calcium and potassium buffers (table spoons per day) . However, my approach uses a more sophisticated test approach so I can map what nutrients are being used and constantly adjust the buffer approach so i can get optimized plant production.




Veined cucumber leaves show iron deficiencies




I also do add a small amount of Iron chelate for the first 6-12 months as Iron is deficient in systems in the initial stages. This approach means all the Phosphorous, Nitrogen and micro elements come from the fish waste, not from a complete fertilizer like Seasol, and I can balance fish nutrient production rates with plant nutrient use rates to optimize the system.

Any plant grows well, but you need to also understand that I run my systems for maximal production of directed plants. For example, I run a herb system completely differently from a lettuce system and differently from a tomato system. Mixed systems (like backyarders use) require a general nutrient profile which can grow all plants and so this isn’t optimized for specific plant production like a commercial system needs to be.

I also mineralise solids and add the supernatant back to the system on a daily basis, so this assists the nutrient profile. The plants experience no deficiencies. This is a no brainer as far as I am concerned. As soon as a nutrient is deficient, you see a deficiency in the plant; usually leaf yellowing or prominent veins or weak leaves etc…If the plant is healthy then it should have all the nutrients it needs to grow and so will contain all the nutrients it usually should have in it.

You don’t need a rocket scientist to tell you a plant is no good and deficient when it is yellow instead of green! I won’t go into the whole “organic certified plants are better than anything else debate” as I am sick of it and the British government spent millions of dollars to categorically prove that organically certified produce is no better nutritionally than any other!! If people think organic tastes better, its probably because it is fresh and hasn’t had all the treatment done to it post harvest as most of our mainstream produce does to extend shelf life etc…


You recently released a fish sizing calculator on your website that helps people figure out the correct fish mass ratio to tank sizes etc. Why did you do that?

I could write a 100 page answer here but will keep it short as possible. The reasons were basically to try and introduce some science and engineering to the backyard field and to provide a predictable design approach for newbies to the hobby.

Jim Rakocy developed his 60g – 100g of 32% fish feed to 1 sqr meter of grow bed area more than 20 years ago, and it frankly astonishes me that no one uses it at all in the backyard field.

Its an easy design approach with predictable outcomes and covers all general aquaponic designs for most plants (greens for the lower 60g end; fruiting plants for the higher 100g end). Easy! My tool also accounts for the bed area required to treat solid fish waste and break it down in time so the bed wont clog.

This comes from established constructed wetland design (another field I work in). As the fish biomass goes up, the bed area required to treat solid waste goes up too. Worms do assist and can lower the bed area required to mineralise solid fish waste, so it does over estimate for worms in the bed situations.

It also outputs the bed volume for biofiltration for people who don’t want a majority media bed approach (this was driven by a recent visit to Hawaii where people wanted to use deep flow with a media bed to treat and filter the system.)





Example of Dr Lennard




People basically design the wrong way around; they choose a fish tank volume then try and match the media bed size, so the tool is to try and assist that. However, you should design the other way around; decide on the media bed then match the fish biomass, feed input and therefore, eventual fish tank volume. So, i wrote the tool as i was writing too many emails with the same content to new people who wanted an answer.


Is your calculator suitable for all types of fish? Trout, Tilapia, Perch etc?

The calculator has been designed to meet all backyard systems and all fish used. It does generalize, and I design commercial systems in a much more intricate way that matches the fish and plant species to be cultured. BUT, backyarders want a generalized tool to meet as many situations as possible, so in some cases it does over estimate, but that is all that can be done for a general situation. So, yes, it can be used for all fish.


What’s the feedback been like to your calculator from the Aquaponics community?

I haven’t had too much feed back to tell the truth. I have heard from Murray (Hallam) and Joel (Malcolm) who have given it the thumbs up and a few people in the USA. I have also had comments from particular forums sent to me; some good, some bad (as expected). I don’t want people to think this is the be all and end all of aquaponic design; as the attached document says, its a generalized tool for those to use who wish to. My feeling is that any negative comments that have appeared on forums is a sign that there are always different thoughts on particular subjects and that is fair enough. I am unsure if it is being used to tell the truth. If it is, that’s great. If it isn’t, then that is the choice of people. On a general note, I don’t read the backyard forums. It is disappointing however that what I do see on the forums, when someone sends me a link, is a number of people who think they are experts and are closed off to this type of info. Those people can and sometimes do have a high level of impact on the thoughts of other, less confident and knowledgeable people on the forums and its a shame that this may lead to those less confident and knowledgeable people not getting access to usable info. However, on the other side, when i have rarely looked at the forums, I see the vast majority of people are there to assist and help others, and that is great. I guess in a democracy (and I fully believe in free speech) you need to accept the full range of views. What I like to see always is fair debate, but I dislike personal nastiness. It would be nice to see the small amount of nastiness disappear from the forums for the good of all.



Is Aquaponics the answer to feeding the planet? Has it got any future?

A topic close to my heart. I must say, I am well over the whole “aquaponics will feed the world” talk.   It won’t!

The world lives primarily on mass produced carbohydrate (wheat, rice, corn etc…). These crops are grown by the Millions of hectares; aquaponics will never replace that.

What I think aquaponics can do is expand the range of vitamins and minerals the world has access to. Many people do starve, but on the whole, enough calories are produced to feed all. However, for proper human health and well being, vitamins and minerals are required and it is this range that many people don’t have access to; basically living on carbohydrate and that is all. So, with aquaponics, we can expand access to vitamins and minerals from the plants and some small amount of additional protein from the fish.

In the western world, the future I believe is niche scale production of high value fish and vegies. In the developing world it is expanded access to vitamins and minerals and protein; that is the future, directed use, not wide scale “feeding the entire planet” type stuff.


Whats the biggest threat to building an “Aquaponics Industry” as you see it?

Charlatans and aquashisters, as my friend Jim Rakocy calls them. I call the current USA market in aquaponics the “American Circus”! It happens with all new technologies, and a good example is hydroponics. People who know nothing come along early and try and sell allot of stuff then disappear after ripping people off.

Then the industry suffers and no one looks at it for another generation. This happened to hydroponics, especially in America, where they have a very low uptake of hydroponic technology. There are bullshitters and rip-off merchants already entering the USA market and so i see the outcome as inevitable. This will mean it may take another 20 – 30 years before wide spread commercial aquaponics is seen.

In terms of Australia I see things differently.

We are very fortunate here that the two major players in the backyard industry have peoples best interests at heart and want to keep improving their own knowledge of aquaponics. I don’t agree with everything they say, do or advise, but I think they are on the right track and have the correct intentions for their customers, and so I openly try and support them as I think they are the type of people the industry needs.


What are your plans for the future?

I am getting by with aquaponics consulting. However, I have found that humans generally (and Australians especially) put little value on advice. You make better income from selling hardware, even if it isn’t that great, than knowledge, which people seem to think should be for free. I also work in other industries; wetland design, water sensative urban design, aquaculture, sewage treatment and aquatic ecology, so my income is OK as I have this wide income producing set of skills. I will continue with all of those. I dream of building my own commercial system that is financially viable and this will allow me to also continue my research at my own facility to further develop my aquaponics design and management approach. It should also shut a few people up who seem to take delight in rubbishing everything I attempt to do in aquaponics.

I also have a new community style system (easy to manage commercial production for community food production) I have developed with Stephen Mushin of CERES environment park in Melbourne and we have just added the fish (about 2,000 of them) so that will be up and producing plants within the next month and so i have a lot of work to do with that at present. I am also going to start to look at other hydroponic methods using other nutrient sources, mostly from waste that is currently just thrown away.




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