Aquaponic Gardening

A Community and Forum For Aquaponic Gardeners

Hello,

I have been lurking on aquaponics forums for over 10 years and this, if I remember correctly, is the first time I joined one. The time is right. I chose this site because of a search I made on Google about the UVI system's base addition tank. To my surprise, delight, actually, Charlie Shultz, who's been fiddling with things on the UVI system for 12 years, answered many of the questions I'd had, and a few that hadn't even occurred to me yet. I'm basically a lurk and search guy, so I'm breaking new ground here for myself.

I recently found myself in possession (30 year leasehold) of a 3 hectare coffee plantation on the Bolaven Plateau in the south part of Laos.  At 1,200m elevation, it produces a small quantity of some of the best Arabica coffee in the world. I wasn't interested in the coffee at first, I fell in love with the 14m waterfall (hydropower). Anyway, I split my time between Thailand and Laos.

I'll be doing a thousand things there, but the aquaponics system takes precedence. My design is pretty much complete, so I would like to introduce it. Obvious mistakes that anyone notices may help others. I have a website and a blog, and the blog follows all the trials and tribulations I'm going through in a humorous if self-deprecating way, but until someone says it's okay to post a link, I will refrain from doing so. A search for "Gandhi-Inspired Aquaponics," which is the title of the article I just posted introducing my system might work. By the way, it's a no advertising, not for profit site. . . Anyway, taking a large lump from my article, here it goes:

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One thing that must be understood about the Bolaven Plateau is that it’s far from being the ideal place to raise Nile tilapia. It can get downright cold there at 1,200m. That’s why the whole system needs to be in a greenhouse. However, the greenhouse design has to allow for a lot of ventilation during the day as daytime temperatures can get pretty high. The average mean temperature is 19.5 C, and tilapia thrive in a water temperature of 28 C. Can a fairly constant air and water temperature of 25 to 28 C be maintained year round without the use of sophisticated heating equipment? Only time will tell, but I think so.

What are the advantages of raising an immensely popular yet tropically inclined fish, not to mention a myriad of tropical vegetables, in the cold climate on top of an extinct volcano? Well, there’s a fancy marketing term for it, I’m sure. Something to do with the fact that the same stuff has to be brought up by truck from the city of Pakse which is roughly 1,000m in elevation away.

This is the aquaponic system I envision without its greenhouse enclosure.

This is the system I envision (without the greenhouse enclosure). It is almost exactly 1/4 the size of the University of the Virgin Islands’ commercial scale system but with a number of modifications (not necessarily improvements). Those familiar with the system at the University of the Virgin Islands (UVI) will first note that the fish rearing tank I’ve incorporated is not very circular. In fact, it’s undeniably rectangular. This one will hold about the same amount of water as 1 of the 4 tanks utilized in the UVI system, about 8,000l. I’ll probably build it with bricks, a mortar render, and a coating of waterproof paint/sealant on the inside. It will face south and the exposed surfaces will be painted flat black in order to get some passive heating during the day. As an aside, the coldest season is also the sunniest. Whereas the UVI system stocks each tank with fingerlings and leaves them in the same tank until harvest, I’ve decided to have one tank that can be partitioned into four areas, the size of each partition being adjustable in accordance with the state of growth of the fish. This will give the little fish less room to frolic about than in the UVI system, but will allow the bigger fish a bit more room to stretch their fins.

Four more or less equally spaced drains in the bottom of the tank will take the fish poo and any uneaten food by gravity to a larger pipe which will in turn divide this waste water among 4 clarifiers, one for each hydroponic tank. Those are the bigger of the blue drums that you see in the sketch at 200l each. A number of DIY swirl filter designs are available on the internet. The solids will need to be removed from a bottom drain periodically, probably a few times a day. This is excellent worm food, or it can be applied directly to my coffee trees. From the clarifiers the water goes first into a smaller blue drum filled with bird netting then into a second blue drum for a bit of vigorous aeration. The first acts as a filter for smaller suspended solids and is also a biofilter of sorts, and the second is for degassing. My system’s solids removal, biofiltering, and degassing may not be up to par with the UVI system, but since it will use easily available materials it will be easy to expand it if necessary.

Water spinach, pak bung in Thai and Lao, growing in the UVI system.

From the degassing drums the water flows by gravity into the hydroponic component of the system. Each hydraulic tank is 40cm deep and will be filled with water to a depth of 30cm. They are 1.2m wide and 12m long. The combined grow area is 57.6m2. This is also roughly 1/4 the size of the UVI system. The tanks, or troughs, will be lined with pond liner (plastic). They will be made by shallowly excavating the 1.2m by 12m area, filling polypropylene bags with the earth, and stacking the bags 3 courses high (30cm). This is called earthbag building. The bags will function as both the walls and the aisleways. They will be covered with burlap to protect them from UV light. As aisleways, at about 35cm wide, they are a bit precarious (especially the center aisleway which has wooden poles projecting upwards every 2.8m), but planting and harvesting are actually done from the ends (the plants will grow on floating Styrofoam boards, each 1.2m X 0.6m, so you just pull them off at the far end and load them again at the front end). Besides, a 35mm aisleway is enough room for a petite Lao girl to dance in circles without falling into a patch of lettuce. I, however, am sure to tumble in once or twice.

Praws, glorious prawns! I'm getting hungry.

One thing I will be doing, which is a bit daring but has seen some success by others, is adding giant freshwater prawns (technically, they are shrimp, I read somewhere, but who cares), Macrobrachium rosenbergii, to the hydroponic component. It is claimed that they will only eat the dead roots of plants, not the healthy ones, and will vacuum up the fish poo and other suspended solids which make it past my homemade instruments of clarification and settle on the bottom. These same suspended solids often cause problems as they coat the roots of the plants, making it difficult for them to suck up nutrients. Supposedly the smaller prawns will take refuge in the roots of the plants to avoid cannibalism by their brethren.

As for the system’s capabilities, on an annual basis, let’s take an example in which the 4 hydroponic tanks were planted 1 each with basil, lettuce, okra, and pak bung (water spinach). The results, including Nile tilapia and freshwater prawns, are as follows:

  • Basil – 312kg
  • Lettuce – 2,100 heads
  • okra – 181kg
  • Pak bung – 2,000kg
  • Nile tilapia – 1,000kg
  • Freshwater prawns – 150kg

Most of the greenhouse enclosure that I envision.

I’m trying to design a system that will run on 500W or less (water pump, aeration, lights). I’ll have plenty of power from my 14m high waterfall, but if it’s going to work in some remote village that’s not connected to the grid, running off of a small, inexpensive hydropower setup is a key to success. In the same strain, the use of easily available materials, including the earth beneath your feet, is essential. With that in mind, I came up with the greenhouse enclosure shown here. The file got too big so use your imagination for the front opening.

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Well, that was probably too long for most of you.

Thanks,

Richard

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Nice,

I expect you can find pumps that will take care of your needs for less than 500W the water pumping needs should be easily handled by a small pump and the air blower will probably be your bigger expense.

I would say go ahead and post the link to your blog.  Perhaps I'm out of place to say it but Plenty of others have links here and as long as you are not spamming or blatantly advertizing, sharing information is what this place is all about.

Thanks!

At the moment, and I'd like to decide by the end of next week, I think I'm going to go with the Reef Octopus Blaster HY-7000W. It's got good reviews and is rated at 7,000 liters/hr. That's about 116 liters/min which is roughly 1/4 of the UVI system's flow rate. It runs on 88W. For aeration, I'm looking at 3 sets of Hailea Air Pump HAP-120 which do 120 liters/min and consume 90W each. This falls somewhat short of the UVI aeration but I can always add another. I considered a big blower unit, some are quite efficient now, but, like a refrigerator, they suck up a lot of watts to get going. That's problematic since I'll be working off of a small hydropower unit. I like the redundancy of having three smaller units. For backup power I'll be pulling a line from my landlord's house which is on the grid but 300 meters away.

My website is at: www.wrongwayhome.com. The post to the blog on the site is at: www.wrongwayhome.com/2012/05/gandhi-inspired-aquaponics/ There you can read more and expand the photos and perhaps understand the unusual title.

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