Aquaponic Gardening – The Duckweed Dilemma!

Aquaponic gardening is a terrific way to grow your own organic veggies and chemical free fish.  Let's take a moment to  ponder the subject of what to feed your "wet" pets so that you can economically harvest the best. The subject of duckweed usually will come up in any conversation when folks passionate about aquaponics get together ... it seems that his tiny aquatic plant can make a big impact!

Duckweed is a species of small floating aquatic plants found worldwide.  It is often seen growing in thick, blanket like mats on still or slow moving, nutrient rich fresh or brackish waters.  Anyone who has ever had duckweed “sneak” into an aquarium or pond knows that this tiny plant can double their mass in under 2 days given the right conditions … this is faster  than almost any other higher plant.  It is for this reason duckweed is considered an invasive plant in many parts of the country and is on the “hit” list in some states. 

Now the real dilemma regarding duckweed is whether it is something you should be feeding it to your fish in your aquaponics system.  The nutritional value of duckweed varies, but most species have protein contents in the range of 15-45% which is good and duckweed is a convenient feed for fish.

• It can be readily grown locally 
• It can be fed fresh and since it floats, it will be consumed by your fish and not decay at the bottom of your system.
• It is used very efficiently by fish such as tilapia and carp, but other species might well cope with duckweed as a component of the diet since it is particularly low in fiber and high in protein when grown under ideal conditions.
• It is relatively inexpensive to produce or may be regarded to have no cost where the opportunity costs of family labor are not taken into consideration.

From the studies I have read, it seems that tilapia do the best with a combination of duckweed and pellets versus just duckweed alone.  See below:

*Gaigher, et al. (1984) compared the growth of hybrid tilapia fish on commercial pellets vs. duckweed. The fish were cultured at high densities in an experimental recirculating unit for 89 days with duckweed (Lemna gibba) or a combination of duckweed and commercial pellets. They conclude that a combination of pellets and Lemna gave the best performance:

When fed on duckweed alone, intake rate was low, feed conversion ratio good (1:1) and relative growth rate poor (0.67% of bodyweight daily). Sixty-five percent of the duckweed consumed was assimilated and 26% converted to fish. When the fish were fed on pellets in addition to duckweed the rate of duckweed consumption decreased and growth rate of the fish doubled with feed conversion ratios between 1.2 and 1.8. Seventy percent of the mixed diet was assimilated but only 21% converted. Fish grown on the mixed diet performed similarly to fish grown on pellets but had a better feed conversion ratio.

I am sure that everyone has had their own adventures with duckweed.  I would love to get everyones input .. so please leave your comments below ...

BTW ... whatever your decision on duckweed dilemma is, I would highly recommend growing in a separate system.  Duckweed enjoys calm or almost still waters, whereas most fish require vigorous aeration of the water and, of course, you want to be able to control its explosive growth and not find yourself up to your ears in it!  

References:

*Gaigher, I. G.; Porath, D.; Granoth, G. (1984) Evaluation of duckweed (Lemna gibba) as feed for tilapia (Oreochromis niloticus X O. aureus) in a recirculating unit. Aquaculture 41: 235-244.

Aquaponic Gardening - Just Do IT!

The art ... or science ... of Aquaponic Gardening requires a plan and action.  You need to consider your location and your climate conditions ... and of course your budget.

I had the opportunity to interview Steve Chin-Yee  right after he got his first aquaponics system up and running. From the arrival of his plans, to actual start up, it took a couple of months ...

Listen to what Steve had to say ...

Steve has studied a ton of aquaponics information and it looks like he is on the road to success.  In his own words "You just have to do IT!"

Thanks Steve, for the tour and interview ... I'm sure that your story will be an inspiration to many other folks out there considering getting their feet wet in aquaponic gardening!

Aquaponic Gardening - Get Hooked!

If you enjoy raising fish, like I do, and you love gardening in the dirt and growing your own veggies for you and your family, then the next logical step is to jump into aquaponic gardening!

So what the heck is aquaponic gardening?

In simple terms, aquaponics is the combination of aquaculture, raising fish, and hydroponics, growing plants without soil. The cool thing about aquaponics is that it simulates a real life eco system where the bacteria process the fish waste "amonia" from nitrites into nitrates which can then be absorbed by the plants and then returning clean water back to the fish ... OK, that might be too much info for the newbie, but if you have ponds or aquariums, it is nothing more than "cycling" or "seasoning" your system.

While some folks do this on a grand scale, in all actuality it can be done simply.  There is a lot of mis-information out there as to the best way to set up a system.  This diagram looks like a swimming pool designer put together this plan ...  This is not the way you want to set up your aquaponics system!






When you decide to move forward on this project be sure to contact someone locally or attend a workshop to help you design the best system for your area.

The main thing to remember is, the more steps you add to your aquaponics system, the possibily increases that you might have a system problem ... by that I mean, if you have 5 pumps in your system instead of 1, you have 5 times the chance that a pump will fail.  In aquaponics, I have found that the KISS principle "Keep it Simple Stupid" is the one to follow.  Use one water pump ( and have a backup) and one air pump (and a backup) and you should be good to go.

So, give it a try with a small system to get your feet wet and experiment.  You may get hooked on aquaponic gardening!

Aquaponic Gardening - Urban Farming with Aquaponics

Aquaponic Gardening .... consider becoming an Urban Farmer!

Urban farming using the aquaponic method is becoming widely recognized as an exceedingly viable method of food production.  Growing plants without soil effectively allows homes, regardless of environmental factors, to grow organic vegetables and raise organic fish varieties. Unlike seasonal gardens, aquaponic aquaculture allows for year round use. Aquaponics have not yet become a widely used food production source yet, but as we look to meet environmental needs and limited land issues, aquaponics has the means to meet these needs.

In a typical urban home, aquaponics stands to drastically replace, or at least ease, the extensive labor requirements of agricultural farming. A typical urban farming system requires about 15 to 20 minutes of daily maintenance.  This results in an ecologically sound food production system, especially when compared to a family farm which requires several hours each day of ongoing maintenance (including land irrigation and pest control).

While aquaponics systems can be developed indoors using an aquarium, or the like, outdoor systems may also be developed within a planting pots, small pools, plastic barrels or natural ponds using either troughs with floating rafts or using vertical tower methods. An urban family home can reap the benefits of their standard garden as well as edible water garden. Many choose to develop their aquaponic water garden in their backyard. Not only will this provide food, but also serves as an aesthetically pleasing water feature providing a serene setting. Though typical ponds are known to attract mosquitoes, the fish within your garden happily control these unwanted pests. The ecological symbiotic relationship between fish and plant is the “key” to its success.

Different varieties of fish and plant life will require different depths and temperature of water. Therefore, several water gardens may be created to allow for an expansive harvest of vegetables and fish. Floating, or “rafting” plants like lettuces and herbs can provide shade which can help keep algae under control. As well, by incorporating plants these floating plants into your garden you are creating an effective water filtration system by way of the plants’ rich roots. 

An outdoor aquaponic system attracts a variety of garden friendly bugs such as ladybugs, which also promotes a further self-sustaining quality. Plant life known to thrive in a shallow and wider environment includes tuber vegetables, including arrowhead and Chinese arrowhead, roots, as well as taro and violet-stem taro. Ideal species of floating plants and vegetables may include the water lotus, water mimosa, water celery, water spinach, and watercress.

Having a combination of both submerged and shallow vegetables in the arrangement of your garden is suggested. Additionally, the edge of your pond provides an ideal habitat for the many species of plant that prefer the constant wet soil.  This will lead to a beautiful garden, and all of this is possible in an urban environment.

While community gardens are a popular method in growing organic vegetables, aquaponic gardening provides an additional earth friendly option for the urban resident. The versatility and sustainability of aquaponics provides opportunity for even the busiest of communities to maintain a water garden with sure success. As the majority of maintenance is required only in initial setup of an aquaponic water garden, and 
continued maintenance being minimal, many families have the opportunity to now take part in urban farming.


Aquaponics information is constantly changing, in addition, so much of it is location specific ... we try to give you ideas and spark your imagination along with your vision!