The Best Plant Growing System?

[GaryD]

Hi,

The most expensive part of most aquaponics systems is the plant growing system.

At around $300 to $400 each, large plastic or fibreglass grow beds (averaging about 2 square metres in area) are particularly expensive plant production real estate.

In a well-designed system, these grow beds are effective (and at that price they'd need to be) but they are not essential for aquaponics.

Using something like a mega bin and a couple of plastic drums for trickling bio-filters, you can build a small recirculating aquaculture system that will enable you to grow your own fish. Depending on where you live, this little unit will cost you $500 (or less) using off-the-shelf components and requiring little in the way of skills or tools to assemble.

This system will enable you to grow useful quantities of fish and all you need to do to maintain water quality is water your existing gardens from the fish tank.......and then top it up with fresh water.

If growing a few fish is your only goal......then this is the easiest way to do it. If you are a successful home gardener, you will get your fish and your plants for the same amount of water that you were previously using just to grow the plants.

Adding a small recirculating growing system to this basic RAS makes it an aquaponics system and that's a good thing for the reasons that I've spoken about......here. This growing system can be as simple as a duckweed tank.

Duckweed Aquaponics bestows all of the microbiological benefits of an aquaponics system and will cost very little to attach to the basic RAS.

Of course, if you've been bitten by the aquaponics bug (and who hasn't), you can use recycled bath tubs or blue plastic barrels.....for less than a tenth of the cost of the large commercially-produced grow beds.

You can make your own grow beds (using brand new materials) of a similar size to the plastic or fibreglass ones for about half the price.

You can use a wide variety of tubs and pots.....and opt for an open loop system using vermiculite or coco coir.

You can use square foot beds, or wicking beds, and water them using water from your fish tank.

Aquaponics can be cost effective. It comes down to the choices you make.

What do you think?

Gary

[mornings]

The most expensive part of most aquaponics systems is the plant growing system.Gary,

That is simply not true. As far as I can tell, it is an unfounded assumption carried on by those wishing to grow fish in aquaponics. Most of what goes into an aquaponics system, in terms of cost, is for the benefit fish, unnecessary for plants.

Here is a comparison for the UVI system if they were using worms (If, we just want to look at the cost of growing plants):

This system has 6 4'x96' floating raft beds. As far as I can tell, the output in plants would be identical. The below UVI system does produce a lot of fish and they certainly have a value -- the UVI system is probably the most efficient one in existence -- but the value of those fish is never discussed when compared to these incremental costs, the actual cost of growing fish.


UVI worm system
1) total h2o: 29,400 gallons 17,000 gallons

2) pumping rate
constant 100 gpm 12 gpm

3) gravel bed req 1340 gallons 1200 gallons

4) fish water/
h2o storage 8200 gallons 800 gallons

5) return sump 160 gallons 1000 gallons

6) feed 7395 lbs. 5178 lbs.

And, none of this takes into consideration the additional cost for the inherent temperature conflict between ideal fish growing temp and ideal plant growing temps (if you are growing optimum fish, you are growing less than optimum plants), the sawtooth effect of having to limit plant growing (less nutrient) because the fish are small, nor does it calculate the higher risk of catastrophic failure when fish are present.

Now, you look over these and figure for yourself what is being spent on plants and the incremental cost of growing fish. What I found was, the cost of growing fish (essentially, the difference between the two systems) is expensive -- in fact, the most expensive part of an aquaponics system.

If your statement were really true, then we should be spending our time finding less costly ways to grow plants. Look no further, I have it: worms. And since fish are the most expensive part of growing plants in aquaponics, we would be looking for better ways to grow fish. Surprise, surprise! They already exist -- have for decades.

We seemed to have lost sight of the fact that aquaponics was created to grow plants (we already had a more efficient system for growing fish) from the waste products of fish. Growing plants did (and does) indeed add cost to growing fish; however, when compared to growing (some) plants in the ground it was still worthwhile. But now, with the advent of worms, one can grow plants without the expense of fish and could grow fish much less expensively(maybe more reliably).

I suspect this is an emotional issue -- it certainly has not been based on any cost accounting that I can find -- and may upset many. However, I invite one and all to show how plants can possibly be the most costly part of an aquaponics system and I invite you to show, from a cost point of view and compared what can be done otherwise, that tradtional aquaponics (with fish) makes any sense at all.

m

[GaryD]

Hi mornings,

I'd suggest that my observation (while poorly qualified perhaps) is true.

I said that, the most expensive part of most aquaponics units, is the growing system.

My comments have to be viewed in an Australian context (where the commercial operations can be almost counted on the fingers of one hand) which is overwhelming backyard-oriented (my particular area of specialisation).

What I should have said was...."Since most aquaponics systems are backyard units......and most of those use flood and drain grow beds.....the most expensive part of these units will usually be the growing system.

If the grow beds use clay pebbles as media (which many do) then the cost goes from expensive to exorbitant.

Four 600 litre grow beds filled with media will cost at least $2500......without the plumbing, support stands and the set up costs......and I can buy a lot of fish tank and some nice mechanical and biological filtration for that money.......and still get change.

I'm not suggesting that's the way that it needs to be but rather that that's the way that it is......particularly if we're talking about those kit systems that are premised on the (often touted) 2:1 grow bed volume/fish tank volume ratio.


If your statement were really true, then we should be spending our time finding less costly ways to grow plants.
And, with the appropriate qualification, it is..........and finding less costly ways to grow plants (in an aquaponics context) was exactly what I was suggesting.


Look no further, I have it: worms.
I totally agree. If you have no requirement for fish, then there are many ways to grow plants and your worm-based approach is one of the more technically elegant ways of which I'm aware.

Gary

[jillybee23]

Gary:

Althoug I am new to Aquaponics, the most money I have spent is on Hydroton and 150 gallon feeding tank ($250US). I purchased 8 each 2X4 8-foot length studs and 1 sheet of OSB and all the pipe fittings for $37.00, pump ran another $44. I used black cement/garden tubs ( 36"X24 1/2" X 8 1/2") as growbeds; cost $11.00 each!. When completed, I expect fo spend $450 - $500 for my system.

I consider it a worth inversment. The question people need to ask is what is their life and health worth?
If they answer everything, then spending some money on an aquaponic system is a worthy investment.

Just my opinion!

[GaryD]

Hi Jillybee23,


The question people need to ask is what is their life and health worth?
If they answer everything, then spending some money on an aquaponic system is a worthy investment.
I think you've made a modest and worthwhile investment, too. In my view, we need to come up with as many low-cost options as possible.....to enable aquaponics to be within the grasp of all people who want to do it.

Gary

[Ravnis]

I am not an accountant but here are some numbers to play with from 1 years operation.

Food: 3 bags. $75
Water 6000 gallons. Commercial rates in my area is 5$ per 1000 gallons. 30$
Electricity $11 a month x 12 months. $132
Cost of fish to start $160. Cost of fish to continue producing 0 (produce own fingerlings).


# of produce 100# of lettuce cost to purchase that at retail at $3/lb is $300
50# of tomatoes Cost to purchase at $2/lb is $100

# of fish 100# average retail price tilapia $3/lb $300
my produce numbers are way low because I have very little skill (yet) at gardening and lost 3 months of plant production to heat and bugs.

Value of food that actually has taste: priceless!

Input is $397 output is $700 difference is : 303

There are other costs associated with greenhouse structure and heating in the winter. These could be zeroed out by simply growing only from mid spring to mid fall and just overwintering a breeding set. It does not cover the one time costs of growbeds and tanks.

This little 100# of fish(tilapia) powers 111 square feet of growbeds and could power a lot more if I could fit it in the greenouse.

I would challenge the notion that UVI is an efficient model of aquaponics. They failed to utilize the one strong reason to grow tilapia. Feed is produced by sunlight in the water in the form of algae. This would bring there feed costs way down. At least 1/2 maybe even 1/4th.

And before you say, but there Doctors. That doesn't impress me, I correct doctors mistakes on a daily basis... I'm a nurse :D

[GaryD]

Hi Ravnis,


I would challenge the notion that UVI is an efficient model of aquaponics. They failed to utilize the one strong reason to grow tilapia. Feed is produced by sunlight in the water in the form of algae. This would bring there feed costs way down. At least 1/2 maybe even 1/4th.
I'd suggest that the UVI model is the easily the most efficient model of aquaponics (of those currently available). It produces consistent quantities of fish and vegetables and has been replicated throughout the world.......and the model is underpinned by 25 years of research and production data.

The system is simple and resilient.

The reason that UVI uses feed rather than algae is that they need rapid growth and consistent nutrient production to fuel the vegetable production......and they are going to achieve neither with feeding algae.


And before you say, but there Doctors. That doesn't impress me, I correct doctors mistakes on a daily basis... I'm a nurse.
And as much as I respect and value nurses, if my health is going seriously wrong I'd still seek out a doctor.;)

GaryD

[jillybee23]

All:

Here are two photos of my system so far. Its taking a little longer to complete because have to work to support my new hobby!

Jillybee

[DaveOponic]

I agree Gary. It's all relative to how much you can afford to spend. I drive a 1984 Subaru and a 1996 Suzuki Vitara. Both 4WD's that cost under ten grand for the two. Sound old vehicles that get us around the roads, into the jungle and onto the beach occasionally.

My growbeds are half barrels. ($25 per barrel at current market price - cheaper if I haggle)

I spend more on good quality Italian made water pumps because I bought several cheap Chinese made ones that didn't last long and two that leaked and gave me a nasty tingle when I put my hand in the water!!!!!

All my Hydro. and AP adventures have been DIY simply because there is no supplier in Brunei.

My 1000 litre plastic tanks cost $ 180 each. To me, that's expensive. I'd love to have some fibreglass ones but we are only temporary residents here and wil return to Qld. in a couple of years.

Is AP an expensive hobby? No. It doesn't need to be, but I do understand that some people are not good with DIY and don't have the tools, experience, time etc. to set up their own tanks and growbeds.

daveO

[kellenw]

"Best".... that means a lot of different things to a lot of different people. There is no right or wrong answer, just opinions.

For me, plants are actually secondary in my systems. My system is all about growing FISH, and the plants are a bonus. They are merely a part of my filtration system, and I get a bunch of "free" vegetables from my filter as a result. "Best" to me, is that by adding plants to my aquaculture system, I cut costs. I use less electricity, less water, my water quality is more stable overall, and it takes me less time to maintain.

I don't want to sell or eat worms, so I don't care how much "better" they are for someone else's system. Now, on the other hand I've considered using them in my growbeds, but never exclusively as my primary biomass.

My system is "best" for ME, because it satisfies my requirements, and helps me reach my goals.... producing massive amounts of healthy, yummy fish.

It really all boils down to an individual's goals and expectations, and what "best" suits THEM.

[GaryD]

Hi Kellen,

A good post.


My system is "best" for ME, because it satisfies my requirements, and helps me reach my goals.......

It really all boils down to an individual's goals and expectations, and what "best" suits THEM.

I agree totally.

One of the wonderful thing about aquaponics is that you can focus on plants......or fish.....or anything in between.

The appropriate technology slant of backyard aquaculture in recent years has even provided us with the wherewithal to grow fish without plants and plants without fish.

For me, it's all about clean, fresh food......and I tend not to get hung up on questions of means and ends.

Gary

[arachdog]

With that in mind Gary maybe you should clarify what your intention was when you started the thread. Do you want it to be a thread to be a random collection of posts where everyone comes in and states whats best for them. Or did you actually have a particular goal in mind like perhaps the most economical, reliable or envionmentally responsible system?

[GaryD]

Hi Arachdog,



With that in mind Gary maybe you should clarify what your intention was when you started the thread. Do you want it to be a thread to be a random collection of posts where everyone comes in and states whats best for them. Or did you actually have a particular goal in mind like perhaps the most economical, reliable or envionmentally responsible system?

My purpose was to stimulate discussion........and to encourage the exchange of ideas and opinions.

And, wherever possible, to stick a boot up the backside of any sacred cows that might be lurking around.

Gary

[Laurie]

There really is no best growing system, what works for you, is the best. I have just put up my new website & it will show you different types, hydroponics, aquaponics, flood & drain, aeroponics etc.
With 66 years of experience between my partner & I, one is always learning.
Check out our website & let us know what you think.

Laurie.


http://www.geelonghydroponicgardening.com

[GaryD]

Hi Laurie,

There's clearly been a heap of work invested in your new site. It's easy to navigate and read.

Good luck with it.

Gary

[mornings]

I would challenge the notion that UVI is an efficient model of aquaponics. They failed to utilize the one strong reason to grow tilapia. Feed is produced by sunlight in the water in the form of algae. This would bring there feed costs way down. At least 1/2 maybe even 1/4th.

And before you say, but there Doctors. That doesn't impress me, I correct doctors mistakes on a daily basis... I'm a nurseRavnis,

I don't know a great deal about the production of algae but to make the equivalent food would take at least 7395 lbs. of dry weight algae, which would be somewhere close to 19 tons wet. And, that assumes a protein content of 32%. If it were less it might take a great deal more. Also if the protein content were lower it would take more fish to produce the same plants (a larger system, more pumping, etc).

And, of course, there is a down side to algae. It clogs, it takes nitrogen away from plants and reduces oxygen levels, which can all result in toxicity. Seems to me, making algae economical would be a real balancing act -- but I really don't know. Maybe you can enlighten us.

I would be interested in seeing your methods (What does it add to the size of the system?) to produce algae and your figures as to exactly how much it would cost to produce the algae and what savings, on balance, would really be there after producing it and suffering with it.

I don't Know Dr. Rakocy personally but he seems to have little bluster or self adulation and, on the contrary, has done a great deal to advance Aquaponics, especially in the tropics and the third world. What mistakes exactly to you think he has made and how would you correct them?

m

[Ravnis]

Algae is an interesting plant. It can get its nutrients from the atmosphere and assimilate carbon dioxide as well nitrogen from the air. The one thing it cant get from the atmosphere is phosphorus and potassium and other trace elements. I basically grew my tilapia for little food(compared to the fish in the bigger tank) input simply because they were eating the algae. I did not have room for a second tank in my shed. I added a clear IBC to the system in the sunlight, even though it is widely argued about here. The water approached 95F and I was concerned that my fish would die. The algae went wild and I could no longer see my fish. The plants flourished as well and my tomatoe plants grew to 6 ft in less than 30 days. The fish quit eating the fish food I threw in except maybe a 1/4 of a cup of fish pellet for 20 fish of approximately 1/2 pound in size. I held my breath for a month and netted them out and they were double the size of my fish I had in the tank in the shed. THese had started out the same size. THey had a much larger growth rate, ate practically no food, and I still had fanstastic plant growth (even if the grasshoppers and caterpillars ate most of it).
The water from the IBC tank ran into the growbeds. Our favorite friends, worms, kept the growbed from clogging up, though I can't say for sure whether they ate the algae or not. The algae was trapped in the two feeder beds as those beds dumped into the sump and the water remained clear in the sump and the main tank in the shed.

I would not say Dr. Rakocy had made mistakes, but rather there are discoveries that will make this production system more efficient. It is extremely energy instensive and that has been the main arguments that I have read against aquaponics being a competitive production system. My little quip about doctors was to point out in a light hearted manner that a lot of people assume just because someone is a doctor they are perfect and know everything. I meant nothing personally against Dr. Rakocy.

Unfortunately, I only have qualitative measurements and will have to work more dilligently in getting quatitative measurements. I wish I could say combining greenwater system with aquaponics was a planned and well thought out system design. I just happened to observe this accident.

[mornings]

Thanks Ravnis. I guess I thought you were going through a drying process, which makes it easy to handle and store but its a lot of work.

I'm no longer interested in fish, but I can still appreciate one who has enthusiasm for trying something new. I also realize that doing this sort of thing on your own when you are not funded with much more than the love of doing something, is not easy and typically takes a long time. Good luck. Is there a thread on what you are doing with algae?

Your plants grew when the water was 95F?

BTW, I don't think worms eat fresh algae, don't think they can/will, however, there is a lot of algae that dies in the dark in a gravel bed and the worms, with the help of bacteria, do clean it up. So, worms can convert a this cheap food source into nutrient too.

Hmmm . . . I'll have to think about that, maybe check with Dr. Clive Edwards or some of the worm people. Maybe I could use the algae to feed the worms. Boy would I love that! I read were algae can contain as much as 50-60% protein -- but it sounds like there is quite a variation. You know? I guess you could see it in the output of the plants. The first problem I had with worms was getting the protein % and nitrate output up. But my solution, while being well controlled, is an expensive one.

m

[Ravnis]

The tomatoes and peppers grew, lettuce growth stopped during the 95 F water temperature. I had ordered shade cloth but it took two months to get it in. If it had come in I would have put it on and probably would have not had this event happen. I will try to recreate it again this summer. But plants grow so fast that I have been able to enjoy multiple crops with a 9 month growing season.

A suggestion for you to try. Take a tub of fresh water with a way of stirring the water , an air stone perhaps, add some greensand(iron and potassium) and supertriplephosphate (calcium, phosphate, some nitrate). Let it get good and green and then pour some of this water into a vermiponics bed. I suspect that you will be surprised with the results. I may even experiment with this myself as I believe you are onto something if fish production is not a personal goal. I doubt my aquaponics system would have been as successful if I had not added worms to the growbeds.



Algae like other organisms will expand to there limit and then start dying off. The tilapia feeding on them helped to provide balance. I believe if you constantly add fresh water to the tank to replace the algae/water you remove that you will be able to keep the algae growing.

[mornings]

Thanks Ravnis. I'll give that a whirl -- or something like it. Growing algae is pretty easy to grow at 37 deg lat. If I leave the cover off the tank, algae starts forming almost immediately. I would have to kill it with heat, drying or darkness. It must somehow ferment -- I think, but I'll report back what it takes. Thing is, if your worms are eating it, they are also feeding your plants with cheap food.

Oh, btw, in fairness to Rakocy and UVI, they may be feeding purchased food because it is a easy way to control nutrient input and the feed is still a very small % input cost. Depreciation of plant is usually the most significant cost. May be a trade off.

m

[Ravnis]

Oh, btw, in fairness to Rakocy and UVI, they may be feeding purchased food because it is a easy way to control nutrient input and the feed is still a very small % input cost. Depreciation of plant is usually the most significant cost. May be a trade off.

m

That and its really hard to quantify algal concentrations if it just forms in a solution. I would suspect but have no way to really measure that algae,like food, will lose some of its nutritional value when dried and processed.

[GaryD]

Hi Ravnis,

You can read about Ronald Zweig who did some work on growing tilapia in solar ponds (translucent fibreglass tanks)........here (http://www.aces.edu/dept/fisheries/education/documents/Primeronsolaraquaculture_aquaponics.pdf).

Gary

[Ravnis]

Thanks for the link, Gary. What I did was combine the green water technique with the aquaponics system.

Before anyone goes wild with this idea they might want to checks out these links.

http://www.aquaponicsjournal.com/articlegreenwater.htm

http://www.bioone.org/doi/abs/10.1893/0005-3155(2008)79%5B92:COLBOA%5D2.0.CO%3B2

I founds some old posts back in 1999 where Dr. Rakocy advised against combining greenwater with aquaponics as it would clog the gravel. I can't tell whether he used worms in his growbeds. All I know in my one time observation, it did not happen and the growbed flourished. I was even able to start cuttings in the growbed. I believe do to the worms. Also I suspect the aeration added by the flood and drain probably offset night time oxygen depletion by the algae. Something threw off my FCR rate as it was way less than 1. What ever it was, it made the economics of aquaponics much better.

Regardless, I do not recommend this process to someone starting out. At least till I run some more tests this summer.

[GaryD]

Hi Ravnis,

For me, the article says more about the ruggedness of tilapia than anything else.

I approach aquaponics from the perspective that water quality management in the fish tank is the absolute priority. I'm inclined, therefore, to rule out anything that diminishes water quality.....and by the sound of it, that includes greenwater (as things currently stand).

That's not to say that there's not some merit in feeding fish algae.....but rather than it would need to happen in a different way.......like pelletising it or something similar.

By the way, I think some of the things that some people believe about aquaponics......like using grow beds to process fish solids (as distinct from removing them and processing them externally).....are driven by outdated information based on tilapia production.

Few fish are as hardy as these creatures and I think that, to premise aquaponics 'guidelines' on tilapia, is a mistake.

Gary

[kellenw]

Most of the tilapias consume algae and diatoms as a pretty substantial portion of their diet in the wild. Tilapia are fairly capable quasi-filter feeders, but they rely quite a bit more on filamentous algae rather than suspended types. Tilapia are commonly grown in greenwater by fish farmers in many countries around the world. However, to get fish to harvest size in a single season in temperate areas, a high protein diet must still be provided as a primary part of their diet. Trying to grow tilapia using greenwater as their exlusive food source would result in a very disappointing fish crop.

Tilapia are indeed one of the most hardy fish we see used in aquaponics (wrt water quality, dissolved O2, etc.), and I tend to agree with Gary that they probably skew some "results" of backyard enthusiasts, causing them to think they've found a better way. I've stocked tilapia in my systems that I setup and filled no more than a few hours prior, ZERO cycle time, and I've never lost a single fish. Try the same thing with many of our North American native fish, and the "results" will most likely be a massive fish kill.