Friday, July 25, 2008

Home-grown Aquaponics

Home-grown aquaponic systems can provide families with hundreds of pounds of fish and fresh vegetables year-round. The system at the Morningstar facility, shown in the picture was built with easily available materials including concrete block and plywood, a waterproof tarp, a plastic barrel and PVC piping.

A complete aquaponic system can be built in approximately 150 square feet, although some larger systems cover many acres. The smallest pond is typically about 500 gallons. Under average conditions, three gallons of water are required for each fish, and every 10 gallons of water in the tank supports two square feet of growing area for vegetables.

Most aquaponic systems use tilapia, a warm-water fish native to Israel where it has been farmed for 2500 years, because they’re extremely fast growing, tolerate poor water quality and use a wide variety of plant-based foods, including duck weed growing on the surface of the water.

A 500-gallon tank can produce about 150 pounds of fish per year, with fish typically harvested every six months at about 1.75 pounds. Tilapia are considered to be highly efficient fish, gaining approximately one pound for every 1.5 pounds of food they are fed. In most home systems, fish should be fed commercial fish food three to four times daily, but automatic feeders are available for families who aren’t home during the day.

Systems designed to produce food, like that shown at left, typically consist of three separate chambers: a fish tank, a biofilter and a hydroponic growing area. The system should be designed so that water is pumped from the bottom of the fish tank into a biofilter (the barrel at the front of the photo) where solid waste is captured. Biofilters must be cleaned weekly, and those nutrients can be directly applied to plants growing in soil.

From the biofilter, water is pumped to the top of a slanted hydroponic growing area, most often constructed with PVC piping. The typical system uses an inert growing medium, such as porous clay pellets or rockwool, a spun glass wool made of volcanic rock, to hold roots in place while water moves through the system and overflows back into the fish pond.

The water in most aquaponic systems will have high levels of nitrates with lower levels of phosphate that encourages green leafy growth, so plants like lettuce, bok choy and herbs are particularly well suited. Vegetables and fruits, like cucumbers and tomatoes, can be harvested but may have more leaves and fewer fruits than those grown with more balanced nutrients.

Water should be tested weekly for pH, electrical conductivity and nutrients, but battery-powered test kits make testing simple. In most systems, 25% of the water should be changed on a monthly basis, siphoning it from the bottom of the tank to capture any remaining nutrients and biosolids.

Home Tilapia Farming

I love this concept. A couple of 500 gallon setups in a greenhouse would provide 300 pounds of fish each year and the heat sink created by the water would keep the plants warm in the winter. 300 pounds of protein has an incredible post collapse trading value, especially when most people are just starting their gardens and have no meat source. Throw in a few chickens and you are set.

12 comments:

Kyle D said...

Very cool. Great article. I wonder if their is a species that is more suitable for further north? Obviously, they wouldn't grow as fast, but that's ok, if you're harvesting them for meat rather than profit

judyofthewoods said...

Another great one for the to-do list. And it seems the Collective Unconscious is at work - just had another similar post in my RSS reader.

Anonymous said...

yuppie survivalism

chuck in vt

The Scavenger said...

First read about this in CountrySide Mag and thought it was a great idea. I would love to try a system like this in the future, got too many iron in the fire now. Great post.

Chris

Anonymous said...

I think you need to make your own soap.

riverwalker said...

Good post! Definitely something to consider learning. Thanks.

RW

Mountain_Tracker said...

Chris, I just thought you might want to know this piece of information so you can make some adjustments... Out here, five 1,500 gallon septic systems froze solid that I know of, mine was one of them so unless one had the room in the house to maintain such a large capacity of water for fish, and kept the house from freezing, I'd be frightful to try something outdoors during the winters here.

Enjoyed the article though!

BigBear said...

Hey Mountain Tracker,

Probably will be to cold, could use the hot tub though.

Anonymous said...

I've seen Tilapia farms in MN and SD. I delivered replacement food to them due to tainted ingredients during the Chinese food poisoning. A self replenishing, natural food supply for them would be a necessity.

BigBear said...

This may sound gross but would maggots work. Road kill in a bucket is easy.

Stephanie in AR said...

Reading through info on small farming/food on another site, led to an area on aquafarming written in the early 70s by Kurt Saxon & Organic Gardening. One article is here:
www.kurtsaxon.com/foods007.htm

and a second, more formal set-up (suggests using maggots as additional food)--www.kurtsaxon.com/foods006.htm

The first site has a lot of info links, some free some not but all geared toward small production, cheap. journeytoforever.org/farm_pond.html

Now back to poultry & pastures...

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