Choosing a tank suitable for aquaponics is probably a no brainer. Many people grab the first thing that suits their budget, but not all tanks are the same and some can positively damage your health and kill all your fish. We take a look at choosing the best tanks for your budget with Aquaponics guru Murray Hallam. The good, the bad and the ugly.

This is a transcript of the 15 minute interview between EcoFilms and Murray Hallam. To listen to the full podcast, jump over to EcoFilms. Its worth a listen!

Murray Hallam believes we need to eat clean unpolluted fish and vegetables. Choosing the right tank is something we need to pay more attention to.

Ecofilms: Murray - Tanks! Its one of the things that most people when they get interested in aquaponics - start looking around for a tank and I know you've got your favourite tanks that you like to talk about but there are many ways of putting fish into a system. Run through some of the various methods people use to get started in aquaponics?

Murray Hallam: Well there's various levels that you can start at aquaponics. There are people - the do-it-yourselfers and they want to be able to use some kind of recycled material if possible and then there are those who would rather buy something that is nice and new to work with and build a quite secure food production system. So they're the two ends of the scale. Then there's all kinds of alternatives in between.

Ecofilms: Because you've got your own favourite method. You are a kit manufacturer. What are your kit systems made from?

Fibreglass tanks will last 50 years

Murray Hallam: We manufacture ours from fiberglass. Marine grade fiberglass, because we believe it's a very durable material and if you're going to make a food production system then it should be good. Thats what we believe because the most important thing in our daily lives is making sure that we can have food security and most people who come to aquaponics are usually interested in food security and food purity.

These are the two top priorities, so we believe that fiberglass being a very durable material and its also inert - chemically neutral once cured, is an excellent material to use for your tanks and your troughs in aquaponics systems.

But having said that, there is obviously a lot of other materials that you can use that are quite good.

Ecofilms: One of the things that most people don't concern themselves with is the very fact that aquaponics is not here for a day or a week or a month. You're going to be running a system that has to produce food for well over six months, a year, three years or five years. We've had our system now running non-stop for three years and I can tell you it's just pumping out an enormous amount of food. But as those years roll by you start worrying and thinking to yourself "Gee, I wonder what's in the tank that could perhaps leach out and become a health issue?" So I think that it's something people have to think about when they choose a tank and what's inside the actual surface of that tank?

Murray Hallam: That is true and that's why we like fiberglass - marine grade fibreglass so much because we know that it's a 50 year product. Its infinitely repairable and it is definitely chemically inert whereas a lot of other plastic type products may well leach things into your system. Just think of the fish for example, they're going to be living in a tank for at least a year and if there's anything leaching into the tank any nasty little chemicals - minute quantities thereof, then your fish have a whole year to pick that up and absorb it. So theoretically you could be worse off using a low-grade tank and low-grade troughs that may be cheap to buy in the first place but you could be worse off in the end. You are trying to escape from the chemical input into your life by doing aquaponics and you can very easily jump right into a worse end in this situation simply by not getting good quality materials in your setup.

Ecofilms: Murray what about PVC plastic? There are some kit manufacturers that are making them. What's your view on PVC?

Murray Hallam: I think it's okay provided you make sure its new and its food safe and it's not something that is being reclaimed. Generally speaking, the PVC tanks and troughs that are black in colour - now this is not always true, generally speaking, they made from reclaimed plastics and therefore you never entirely sure whats in them. Coloured ones are generally okay provided they are stamped and approved as food safe.

Rainwater tanks can be modified for Aquaponics

Ecofilms: What about people that immediately go to hardware stores and look for tanks that have another use - say rainwater tanks here in Australia? Whats your view on repurposing rainwater tanks for Aquaponics?

Murray Hallam: Rainwater tanks are quite okay. They're actually here in Australia anyway, they're made from good food safe plastic material and are quite good. Its a good use for a rainwater tank not the cheapest (method) really but it's it to good use for a rainwater tank to turn it into an Aquaponics system. Lots of people cut them in half, use the bottom half for the fish tank -depending on the size you want to get of course. Its a good way to go.

This bathtub aquaponics system is a low tech solution

Ecofilms: And bathtubs? There seems to be a lot of people that go to the local rubbish tip looking for bathtubs. Can you tell us whats your view on bathtubs?

Murray Hallam: Well its a good way to get started. If you're a person who doesn't have much money to spend at this particular point when you decide to start in Aquaponics, then putting together a system out of a few bathtubs is not a bad way to go. I wouldn't want to think it would be a permanent idea but it's certainly a good way to get started and to just feel how it goes and how it works and to just see if you can do at your place. Most people that we've encountered that start down the bath tub route, end up upgrading to something better and that's not a bad way to go.

Usually old bathtubs, depending on how old they are of course, are enameled. They could be metal with an enamel coating which of course is inert and food safe. There are plastic tubs, some of which are cheap and nasty made of materials that are not food safe and then the better quality fibreglass bathtubs are quite good. Once again, if you're going to use recycled materials you need to find out what kind of material it is and if you have any doubt do not use it! Simple as that.

Ecofilms: And this brings is down to the minimum size of the tank. In your view offering the best outcome - is there an ideal size in gallons or cubic meters? The dimensions of the tank that will give you the most stability? Is there something along those lines that you'd recommend to an average backyarder who wants to grow food for their family. What sort of minimum or maximum size would you recommend?

Murray Hallam: Look, I've seen people build quite successful little tiny aquaponics systems out of a couple of old aquariums and make it work but the more water you have in the system, the more stability you are having in both pH and temperature and that becomes more and more important for your fish that you have pH stability and temperature stability. As much can. So we have found in our part of the world - south-east Queensland that a tank of about 1000 L or 250 gallons of water is a good size because of that size you do have a measure of stability in both those parameters and thats important because if you spend the whole time chasing pH, trying to keep it right and also difficulties with large temperature swings when is a hot day, the temperature of the water goes up - if you got a small volume of water then your water temperature will tend to follow the temperature of the day. Whereas in a much larger volume of water - it takes a lot longer to change that temperature which makes your fish a lot happier and a lot more contented, and your plants too by the way.

Huge temperature swings in the water is not good for your plants. Roots zone temperature can become very important in growing your plants successfully.

Concrete tanks are very alkaline

Ecofilms: What about those people that want to do it themselves and use concrete? They fill it up with water and then throw fish in. What you say to them?

Murray Hallam: Well they'll have problems with their pH. Concrete has got a lot of lime in it and even old concrete tanks still have a lime content which will tend to make your system alkaline and we need to have our system at around about 6.5 pH for everything to be ideal. If you have a concrete tank you'll find very hard to keep it down below seven. Very difficult indeed, so if people want to build larger concrete tank out of something like concrete blocks, then they should be prepared to coat it with something. Some kind of paint that once again is inert and safe for human use, potable water use, but that adds more expense.

stainless steel milk vat

Ecofilms: As an alternative you can get stainless steel, copper or zinc tanks. Say someone found one in in a garage sale or auction and they came home with a large copper tank. Would that be suitable?

Murray Hallam: No definitely no copper. Its not good for fish. As we know, they paint the bottoms of boats with copper paints in order to repel fish and crustaceans and barnacles and the like, so it's not good for our fish to be in a copper tank. Likewise zinc, in fact zinc or galvanized tanks are poisonous to fish. Quite definitely so. Having said that, some of the newer products that we see used in Australia to make metal tanks - one that is called zinc-alum is not so bad because that actually has a very fine plastic coating over it. Then we talk about stainless steel tanks? I've seen customers find old milk vats for example from a disused milk factory and stainless steel tanks are really very good actually. If you are going to build one from new then expect to go a visit your bank manager because they are very expensive.

IBC or Tote tanks are an economical way to get started

Ecofilms: Now you recently released a DVD called DIY Aquaponics where you make a CHOP2 system from IBC tanks or tote tanks as they call them in America. What about those sort of systems? Are they quite safe?

Murray Hallam: It's really a good way to go actually for a recycled materials usage, to be able to use those IBC's or tote tanks. They're available almost everywhere in the world you'll find them. Just be careful that you find ones that have not had toxic chemicals in them because obviously agricultural chemicals are transported in them. The tanks if you obtain them from the first user, they will still have a label on them showing what was transported in them. If you get one that's had some safe material like for example some kind of acid that washes out very easily with water, there are a number of ones we often obtain for customers that have had pool chlorine in them. Tthat's quite good as it washes out quite well.

Other ones have been used to transport bulk food substances, like orange concentrate, orange fruit juice concentrate on that kind of thing. They're quite good to use. You'll need to paint or protect the IBC tank somehow from sunlight because the plastic material that is used will eventually break down with UV light so they are not a long-term option in that regard unless you go to the trouble to make sure that they're shielded from direct sunlight.

Ecofilms: What about people that they want to use plastic sheeting? They would dig a hole in the backyard and there are going to lay sheeting over it and somehow cover it over stones and so on and make a pond Aquaponics system. What's your view on plastic sheeting?

Murray Hallam: Well actually its not a bad way to go. Once again provided you buy good-quality plastic pond liner. Or a dam liner. Make sure it is suitable for potable water or human water use. Its not a bad way to go. You can build a container of timber for example or lumbar. Get the shape you want and then line it with the plastic liner. Its not a bad way to go and its reasonably economical as well. On the downside, when you're putting your media into it, your gravel media into it - you need to be careful not to puncture the lining. If you're going to keep crustaceans and for example, or some kind of Yabby or claw-fish, they might tend to bite holes in it which is not good, but for ordinary fish like Jade Perch or Silver Perch, Tilapia, those kind of finfish, it works really quite well.

Ecofilms: I wonder what sort of life you'd expect to get out of a pond liner?

Murray Hallam: Well the sun is a marvelous thing. It will break anything down eventually. I would once again wanted to be protected from direct sunlight and make sure that it is housed in a good greenhouse or the like. Most of those pond liners that I have seen have got an estimated life of about 10 years. That's provided their protected in the appropriate manner and they don't become punctured or in any way compromised like that. But it's not a bad way to go. We've seen commercial systems. We were in America recently visiting some different farms and we found that they had made their troughs out of timber or lumber and lined them with the plastic liner that we've just described. It works quite well

Ecofilms: So you'd recommend if you're building a small-scale commercial floating raft system you'd recommend that you did it in timber and plastic liner?

Murray Hallam: Its certainly one way to do it. That's for sure. It's quite able to be done by people with moderate skills. Its not a high skill thing and so it can be done by people quite well.

This article was first published on My Green Australia. My Green Australia is a resource of information about living green and healthier in Australia. We want to protect and cherish our country and preserve the natural beauty of Australia for many generations to come.