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

[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.