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Friendly Aquaponics
Commercial Newsletter

Number 15
February 18th,  2013
Images from our farmily aquaponics farm

The Mysteries of Aquaponics, Part 3: How Much To Feed Your Fish For Good Vegetable Growth:

So if you don’t need to follow complex numerical systems for feeding your fish, weighing out the food each time, and if you can get good vegetable growth with as little as 0.05 pounds of fish per square foot of raft area, what do you do? It’s up to you how many fish you choose to run your system with, but you should know your costs and return, as we indicated in the last newsletter.


As far as feeding goes, we feed the fish what they will eat (ad libitum) one to three times a day. It works fine, and, judging by our excellent results in the plant growth department, there is no need to slavishly adhere to some specified 'feeding ratio" in order to turn a profit with a commercial aquaponics system. There is something you need to know in order to understand why these organic aquaponic systems work with such a wide range of fish densities.

That is that we (and one of our students, TBMK) are the only ones in the world to have run both the original university type systems (with their pH adjusted with caustic chemicals), and our USDA organically certified systems, which have their pH adjusted with calcium carbonate (crushed oyster shells or coral beach sand, both highly innocuous substances). As a result, we’ve seen the performance of both, and there is a huge, obvious difference; which is seen in nitrite and nitrate levels.

The university recommends, and we began with, calcium hydroxide and potassium hydroxide as pH adjustment chemicals. We call these the "caustic" pH adjusters, because they are. We switched to calcium carbonate because it was necessary to achieve USDA organic certification: the university systems as operated are not certifiable.

The university told us they adjusted pH "once a month or so", but when we had our pH dive in a matter of a few days once, I called “the university” and got this explanation: "We had that happen to us also: for three weeks or so we had to adjust pH every couple of days. We don't know why it happened, we don't know why it stopped, and it never happened again; this would be a good subject for a study". This is what a PhD says instead of "I don't know", because it is so very difficult to admit you don't know if you are the professor.

Before we went organic, while we were still using the university pH adjustment chemicals, we had nitrates anywhere from 40 ppm up to 200; and we had never noted a correlation between fish feeding ratios and nitrate levels.


The literature from the university (and my notes from the class lectures) insisted there was such a correlation, and also insisted that there was a direct correlation between the frequency of cleaning the net tanks and the amount of nitrates released into the system. They even directed us to "clean the net tanks more often for a lower level of nitrates in the system, and less frequently to promote a higher level of nitrates in the system".

During this time we kept scrupulous records, and charted pH against water temperature, nitrites, nitrates, ammonia, DO, and everything else. When we tried to make sense of these numbers with a graph, it was just a child's squiggles, with lines crossing all over each other instead of indicating the possibility of trends or statistical likelihoods.

One of our early students duplicated a university system and then found he also was totally unable to raise or lower nitrates with this method; they went where they wished, with no apparent relationship to the amount of fish feeding or frequency of net tank cleaning, just as ours had. So we had two systems that we could see that didn't exhibit this claimed behavior; and one system (the university’s) that we couldn't see or test, and in which they claimed this behavior occurred. Which to believe? We leaned towards believing what was in front of our own eyes, of course.


Rose and Dad and two of our "Delicious Fishes". Although we eat them with respect, we don't give them names because then it's harder to eat them.


This was cleared up when we re-read some printed university materials in which they measured ammonia, nitrites, and nitrates over a year's period. We noticed that nitrate levels went from "in the 40's" down through the 20's, 10's, and down to 3 ppm during a three-month period. When asked for an explanation, they simply said: "Yes, that's interesting, we should do a study on it". In other words, even though the university claimed they could manipulate nitrate levels, the question remained: "If they can, why didn't they do so? Why did they let their system get down to 3 ppm nitrates without doing anything about it?". I have never made a big deal about this because I never wanted to embarrass the university; we are deeply indebted to them and their research for the information we began with; we didn't have the budget or the time to figure out all that stuff on our own.

But to publish erroneous information on techniques that aren't duplicable is not good scientific procedure. As noted, neither we nor our student were able to duplicate the university’s information on nitrate levels being affected by fish feeding or frequency of cleaning the net tank.

What we did notice, as soon as we switched to calcium carbonate for adjusting pH (in order to obtain our USDA organic certification), was that the nitrate level dived; it went down to 10 ppm, then to 5, then to 3. I told Susanne "our nutrients are disappearing, and our plants are going to die".


But the nitrates didn't disappear, they leveled out at 3 ppm (that time) and the system kept on growing in an explosive manner, as we had come to expect of aquaponics systems generally. You will see claims by various experts that aquaponics systems “must have” nitrate levels of 40 or even 60 ppm or they will experience all kinds of nutrient deficiencies.


We haven’t seen any deficiencies in six years in any of our 6,000 square feet of systems, except a single instance of a potassium deficiency which was fixed with a one-time foliar spray. And this is in systems which have run for months at a time with zero measurable nitrates; measured with a test that clearly shows 1 ppm. I suggest that this is a reasonable statistical sample to draw at least a hypothetical conclusion from, which is what I’m about to do next.


(Next: Where the heck are the nitrates coming from anyway? This will all make a lot more sense when combined with the information in #4 of this series! Thanks for listening!)

Friendly 2014 Commercial Aquaponics and Greenhouse Training Schedule:

Texas Training in May, dates to be announced

Tennessee Training in May, dates to be announced

California Training in June, dates to be announced

(Below) One of Ben and Alysha Godfrey's aquaponics systems in a greenhouse in Milam County, Texas. Their system water tastes great! It has a pale blond hue, with a hint of apple and pear blossoms. lettuce2-385px

(Below) Another of Ben and Alysha's aquaponic greenhouses.

(Below) Tim drinking water from one of Randy and Katie's aquaponics systems at a Tennessee training. "I've been doing this for six years; I'm certain the food from these systems is safe and healthy" (Tim).


These five-day trainings allow you to travel during the weekend so that you only need to take a week off your busy life to attend, and include our $999 DIY Commercial Aquaponics package, $998 DIY Farmer's Market Aquaponic Solar Greenhouse package, and new $295 DIY Commercial Tilapia Hatchery manual as course materials, plus our Plywood/Epoxy/ Tank manual, CAD construction drawings for all greenhouses and aquaponics systems, and much more!

(Below) Randy and Tim showing attendees at a Tennessee training how easy it is to use a DO (dissolved oxygen) meter to measure oxygen levels in the vegetable troughs.


More details of the Aquaponics Technology course here.

More details of the Aquaponic Solar Greenhouse course here.

More details of the Commercial Aquaponics course here.

(Below) Randy and Katie's Chinese-style Aquaponic Solar Greenhouse in Tennessee in the February snow, 2013. 70 degrees inside and you had to take your coat off when working with the vegetables!

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An Aquaponic Solar Greenhouse with the participants in our second June 2013 course in Tennessee!

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The Friendly  Aquaponics Way Video!
Back Issues Of Newsletters Now Available, Click Here!
Trough Liner Distributors:
West Coast USA
East Coast USA

Click here for Trout fry and fingerlings directly from the hatchery to you!

Spanish Language Micro System package now available!
Free Farm Tours

Aquaponics tour at the Friendly farm!

We hold a free Farm Tour on our farm the FIRST Saturday of every month at 10:00,  focused on growing food with aquaponics.  Click here for information. See you there!

If you are a school, a non-profit organization, an organization working with the poor, Native Hawaiians, or ex-inmates, or if you are a church, we will hold a free farm tour for you anytime. You DO need to email us first to schedule, or we might be out on errands!


Thousands of inch-long "fifty-cent" baby tilapia from our "backyard" hatchery.


What they turn into about a year later: a beautiful 2-pound white tilapia grown in the fish tanks of our aquaponics systems.


Micro System Classes!

Our four affiliates are now offering Micro System courses.

Click here
for a listing of affiliates and course locations!


Our new book: "Aquaponics The EASY Way!" is done!

It covers how to successfully build and operate tabletop aquaponics gardens from 3-1/2 to 18 square feet in size, using materials and equipment you can buy locally at Home Depot, Lowe's, and Petco.

The "3.5" costs you under $100 in Hawaii (where things are expensive) and the "18" costs $320.30. Click here to get our free "System Cost Calculator", an ExCel spreadsheet that you can put your own local numbers into (for parts) to find out what your system will cost you.

To purchase this E-book for only $29.95, click here. It's an excellent textbook for aquaponics for students from 6th grade on up. If you are a teacher, school administrator, or other faculty member, email us for information on pricing and volume discounts for textbook use.

The "Tropic Bird Chronicles", #152: "The Cat Who Walks Through Walls"

For those of you who have read Robert Heinlein's "The Cat Who Walked Through Walls", that cat lives with us.


His name is Stinger. Purebred Siamese, about twelve pounds, chunky around the head and neck; he's full of testosterone and "don't mess with me" attitude. He appears, without any announcement, inside the house at random intervals.


We all know what his real goal is: to back up to some unsprayed piece of furniture and let loose all over it. He simply wants to make the inside of the house uniquely his, just the way the outside already is.


When he’s caught, he crouches down like I’m going to clobber him, then immediately walks over to rub and purr against my leg. I affectionately refer to him as "my dog", because he then rolls over, just like a dog, exposing his belly for me to scratch.

Here's why this is a mystery: this has happened more times than I can count, when I had just thrown him out, when no one else was at home but myself, and I had previously checked ALL the doors and windows inside our huge house to make sure they were closed. There is simply no other plausible explanation.


The fact that my cat can walk through walls proves to me beyond a shadow of a doubt that not only are all the possible universes connected, but that pieces and chunks of them may appear (according to some as-yet-undiscovered universal chunk theory) at certain times and places in yet other universes (and vice-versa).

Here's how it works: my cat can see when a piece of wall from another universe appears for a minute or two in the middle of a wall that exists in our universe, and then he simply walks right through that patch of wall into the house.


This is possible because the molecules that comprise the patch of wall from the other universe are vibrating at a different rate than the matter he's made from; it's effectively transparent to his solidity and doesn't provide any bar to his passing through. He sees it just like we see a door in a wall, but his "door" just looks like a homogeneous wall to us, because our human eyes are unable to see the way cats do.


(loud applause!) Thank you, thank you.

However, given my lack of higher education, this is probably destined to be my total contribution to the debate regarding the possible existence of alternate universes and realities.

And frankly, as far as
David Deutsch is concerned, if he had ever brought back a single thing from any other universe than the one we have all more or less agreed we exist in, that would surely be proof that the other stuff he's claiming could at least be possible.


And if that’s ultimately true, I’d love a personal introduction to Santa Claus or the Easter Bunny, OK?

Aloha, Tim.....

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