Thursday, August 27, 2009

Aquaponics Calculations & System Planning

I recently ran into some frustration while trying to recalculate an aquaponics project I am working on. The project consists of 6- 4'x8'x8" ferro-cement grow bins, and will eventually use a 4.5'x6' ferro-cement fish tank. The basic formula is 200lbs fish = 400 gal water = 800 dry gal of medium.

I originally calculated the number of grow bins needed using a 4'x8'x12" size but we never made any bins that deep- with the exception of one 10" deep bin the others are about 8" deep. However this still cannot be used in the calculations because the functional depth (the depth the water shouldn't go above) is 6" so the formula should be 4'x8'x6". Using this I worked the calculations:
  • Convert all numbers to the same unit of measure (inches)- 4'x8'x6" = (4'x12") x (8'x12") x 6", or 48" x 96" x 6", or 27648 cubic inches.
  • Convert cubic inches back into cubic feet- 27648 cuin / 1728 cuin (1 cubic foot) = 16 cuft
  • Convert cubic feet to US dry gallons using website ( 16 cuft = 102.86 dry gallons (dgal)
  • So each of our grow bins needs 102.86 dry gallons of medium like pea gravel
  • We need 800 dgal and we have space for 514.30 dgal however the 514.30 number is using only 5 of 6 grow bins of the above mentioned size. We also have one bin that is functionally 4'x8'x8" = 21.33 cuft = 137.12 dgal.
  • So 514.30 + 137.12 = 651.42 total dgal
  • Therefore 800 dgal - 651.42 dgal = 148.58 dgal needed to meet the requirement for the 200 lbs of fish.
  • One solution would be to build another grow bin functionally 4'x10'x8" = 26.67 cuft = 171.49 dgal.
For this last bin we could use 2"x10"x10' lumber, some 2"x2"s for corner supports, and a liner. A 4'x10' support table would need to be built from 2"x4" lumber. Using this method would help us get the last bin in quicker and test the liner method.

The system I build for my microfarm will not need to be so large but will utilize the same formulas. I will probable build a ferro-cement sump tank as well as long ferro-cement grow bins. I was going to use plastic food grade barrels but have only found a couple and they have their own problems.
  1. They are... wobbly. They warp and sometimes aid in water spillage. They need cross bracing
  2. They have rounded bottoms making them a little difficult to calculate medium
  3. They are harder to mount on support tables
If I just build the grow bins I can make them whatever size and shape I need. On the other hand I might just make them from wood and liner. I will also consider different tops to go on them so I can have mini-greenhouses, bug screens or shade screens.

The fish tank needs some work too. I may put a drain in, or I might just jack it up and use a pump, or even manual siphon vacuum for cleaning the bottom. It just depends on... how I'm feeling that day I guess. I am going to try to utilize a overflow pipe that sucks solids from the bottom, but it may not work.

Lots of work to do.

Anthony Faircloth

Tuesday, August 25, 2009

Beginning Summary

To Begin With:
I have less than half an acre but my plan is to raise chickens for eggs and meat, rabbits for meat, fish for meat, fruits and vegetables. This post will summarize where I'm at and what I have planned. Future posts will be updates as to my status and observations.

I have built a 4'x8' chicken house made almost exclusively from chicken and welded wire. My theory is that in North West Florida the heat is the predominant factor so the floor is 1/4" welded wire supported by 10 gauge wire connected to turnbuckles so it can be tightened as needed. I have chosen to raise bantam (small) chickens so I built the nest box 10"x10"x8', a 8' long ladder made from 1"x2"s allows entrance as well as acts as perches. I am not comfortable with letting the chickens roam around the yard so a 4'x16' chicken yard will be built to allow the chickens to move around while being protected by animals. I still need to figure out the the placement of feeders and waterers.
I hope to select hens that are both good layers and brooders. The laying attribute is obvious but because of my limited time I need the hens to raise their own young. I will research the best overall breed prior to ordering. I would like to get a rooster, and have cleared it with my closest neighbor, but wonder how long we will need to get use to it's incessant vocalizations! On the other hand I can then have the possibility of new chicks. I hope to install the new chickens by the Fall of 2009.


I have constructed four 2'x2'x8' cage frames. They are all use 2"x2" lumber covered with 1/2" welded wire. Two of the frames are divided into two cages each making four cages total. These are the breeder cages. And two of the cage frames are divided into 3 cages each making a total of 6 cages I will be using for "fryer" cages- a place to fatten the young rabbits.
The cage frames are stacked in twos between buried 4"x4" posts with a isle running between the two stacks. Each stack is roofed with leftover roofing shingles. I have a slight bow in the roofs due to a miscalculation as to the weight of the shingles but I will be correcting this. Trays are mounted below each cage to collect the feces for composting.
The cages are competed and only need to be furnished with nest boxes, feeders and water bottles.
I want to order something other than New Zealands, or Floridians (white rabbits). I will try to get my breeders installed in the Fall of 2009. I intend to have two breeding pairs.

I have been working on an Aquaponics project with another group called Sustainable Missions (see their FaceBook/MySpace accounts) so I plan to duplicate a smaller version of this system on my microfarm. I have a small aquaponics model on my front porch that has been supporting several goldfish for a few months. I grew jalapeno peppers in the grow bin with no extra effort from me.
I have a 400 gal poly tank and will need to build some grow bins as well as a sump prior to installing the fish and planting the bins.

Fruit Trees:
I planted two grapefruit trees this year in 2008 and will probably not produce anything for a couple years. I also planted two Santa Rosa plum trees that may bear something next year, as the figs might do since they have already produced several figs already. I have determined that I will top these trees when they get around 12' so they will not become a problem for storms and hurricanes.
I also planted 6 blueberry bushes of three types. A local blueberry grower told me to pull the blossoms from the bushes for the next couple of years so the growth will go into the bush.
I hope to add a couple more citrus trees (lemon and Satsuma), then either peaches or apples. I may also plant some strawberries in some unusable areas like fence rows.

This year I dug and tilled several long rows about three foot wide. I purposefully left the grass between the rows which in the end caused trouble by allowing weeds to invade the rows. Since I have limited time to pull weeds, and my family is not 100% on board with the microfarm, I will need to develop and better system. I will be building formal raised beds using 2"x10" lumber and weed-block fabric on the bottom. I will also integrate a PVC watering system into the new plan.
Once the beds are built the tops can be built; plastic for early season plants (green house), insect screens, or shade. The beds will be filled with a fertile mix of my own compost and purchased soil amendments. Other than the weeds I neglected soil preparation this year and had limited success in the new beds. This should not be a problem once I begin composting the animal manure.
As far as crops I will be sticking to the old standards, but I will plant some root crops to begin experimenting with drying and feeding them to the rabbits. Also, experiments on cutting and storing bean hay.

What Is Left:
I have several things the need to be completed prior to installing the chickens and rabbits.
  • Chicken yard established
  • I need to consider further sheltering for the chickens, not just nest box
  • Ramp for chicken house
  • Two rabbit pellet trays built and installed
  • 4 rabbit nest boxes built
  • Rabbit feeders and bottles purchased and installed
As far as the fish...
  • Build & mount grow bins
  • Build sump (ferro-cement); overflow drain
  • Plumb poly tank; drain and supply lines
  • Configure system; set things where they go
  • Plumb system; supply and drain
  • Purchase, install and test pump
  • Acquire fish of some kind to prime system.
At some point I will also need to complete some home repairs. Things needing done since Ivan! I would also like to redesign my compost bins. And level/back-fill some areas of my yard.

My wife, Gail, has also suggested that we also get some pygmy goats to raise and milk. If we do thin we will need to bring in food since there is no way I could raise enough food for them. The good news is that there is a farmer at the end of the road who might sell me some hay and straw. However, the goats are certainly further into the future.
I am also reading up on bee keeping. I would only need one hive and I'm thinking of it in the context of honey for medical purposes, not just to eat.
I also have a dream, and the beginnings of a plan, to build a little (14'x10'x10') domed ferro-cement farm house for one. It will be my office and part of the experiment using a water catchment system, saw dust toilet, PV-DC electric system and other sustainable low-tech features.

Stay tuned for other posts!

Cantonment- 090825