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Friendly Aquaponics Newsletter
Number 35
May 2nd,  2011
Images from our farmily aquaponics farm
Aloha Friend,
We've grown an organic spring lettuce mix for three years now, and finally hit an invisible wall. As we traced it back, we found we had purchased an infected batch of seed and mixed it with nine other varieties of lettuce seeds, then planted the result. This was $1,800 worth of seed; a year's supply for our operation.

Unfortunately, the disease didn't affect the plants much until they were well along in the development process, around five to six weeks, with harvest due in a week or two. We noticed blighted plants wilting, brown leaves, and the disease spreading to plants near the ones initially infected. We took samples to the County Ag Extension Agent, and he is analyzing them at the lab to tell us definitively what they are. Bottom line is, we weren't careful enough! We will lose about $10,000 of income from this one event alone, and will miss shipments for a month or more while we sterilize and get back on track.

We'd had this disease show up before, but in such isolated instances and locations that simply removing a plant or two kept it under control. This time, it was every tenth plant in a system that holds 35,000 plants, and with that kind of "inoculation", disease control efforts didn't make much difference.What is the "good" news here? Because this happened to us, it never needs to happen to anyone else!

To make sure this never happens again, we need
to not only mix our lettuce seeds in MUCH smaller batches (ever had to throw away $1,800 of seeds? It really hurts!), but also do test plantings to discover any such problems in smaller, sterilizable aquaponics systems (that are FAR away from our commercial systems) before we plant them in our commercial systems. If we'd planted these seeds as a test planting two to three months before we needed them, we would have caught it, tossed the ONE seed batch responsible, sterilized the test system, and gotten some more (uninfected) seed from the seed company in plenty of time to avert disaster. We're going to write this up as a standard procedure and include it in our Commercial Aquaponics manuals.

If you're interested in
commercial scale aquaponics, please take a look at our Commercial Aquaponics Trainings (Special Offer in right sidebar of this email), where you will learn more about real-life operation of a commercial aquaponics system than you can anywhere else in the world. For smaller home backyard and apartment systems, please read on:
Purchase Construction Plans and Operating Info for 4 Different Sizes of Apartment/Condo Aquaponics Systems $49.95

Our Apartment/Condo System package includes new and easy-to-understand building instructions and complete operating information for 4 different sizes of small aquaponic systems based on our years of experience operating a commercial aquaponics farm. Anyone can build a system out of plastic barrels, but operating one successfully without good and easily-understood information can be frustrating. You simply use the "Daily Operations Checklist" in the manual and follow the step-by-step instructions on your way to success.

We spent hundreds of thousands of dollars, hundreds of hours, and built our first commercial aquaponics systems with FAR less information than this manual contains. We included all the information learned from that experience in this manual so you don't need to make any of the same mistakes we did.

Learn about our Apartment/Condo Systems!

Aquaponics Nugget #35:
Nutrient and pH Levels In Organic Aquaponics Systems
(Part 2)

We ask if anyone present on our farm tours is a hydroponics grower, and usually get several hands up because aquaponics often attracts hydroponics people looking for a better way to grow. I tell them it has been a month since I checked pH, and would anyone like to bet me $100 that I can go up to ANY of our systems and measure a pH of between 6.9 and 7.1? Someone will start to take the bet, then think better of it and say "you wouldn't make a bet like that unless you knew something". It's true, I KNOW from years of experience it's a safe bet; pH is rock-steady in organic aquaponics systems. The "experts" don't know why, because they've never operated one.

The reason pH is so steady is that we use calcium carbonate to balance the pH in our systems rather than calcium and potassium hydroxides, which are NOT organically certifiable. The action of the hydroxides in lowering pH in a system is relatively short-lived; we've had to adjust pH as often as once every two weeks back when we were using them, and my teacher told me once "Once we had to adjust pH every two or three days for about two weeks; and we don't know why". The calcium carbonate, on the other hand, acts as a buffer, which brings the pH up to a certain level, then stops dissolving into the system.

We had a student who called us up one day and said "Tim, I think I might have put too much calcium carbonate (coral beach sand in Hawaii) into my system. I asked him how big his system was; "120 square feet", he says; and how much he put in "about half a five-gallon bucket", he responds. We add about two cups to a 3,300 square foot system when we add it, so I was reasonably concerned when I asked him the next question: what was his pH? "about 7.2". So, we're not ABSOLUTELY certain, but we think it is very difficult to add too much and damage the system.

Here's a warning: Although we haven’t run into it yet, it is possible to create a condition called “nutrient lockout” by increasing your pH to too high a level. If your pH is too high, nutrients such as iron, boron, magnesium, potassium and others become unavailable to the plants because of the interaction at the molecular level. This is called “nutrient lockout”, and they really mean it, because it doesn’t matter how much iron or other supplements you add to your system if your pH is too high. At a high enough pH, the plants won’t be able to access them, and will continue to exhibit symptoms of nutrient deficiencies although there is plenty of that specific nutrient in your system. We can’t give you a hard and fast number for what is too high. We DO know right around 7.0-7.1 is safe and productive, and we've started several large commercial systems with water having a pH of 8.0 to 8.2.

This business with the pH is unheard of, and we frequently get incredulous hydroponics growers ( and people running chemical-based aquaponics systems) telling us we must have measured it incorrectly or are just plain lying. We get the same reaction to the measured levels of nitrates in our systems.

We have one 3,500 square foot system that consistently measures 1 (or LESS) ppm nitrates, and two 1,024 square foot systems (that we have WAY too many fish in) that usually measure between 3-5 ppm nitrates. They ALL grow vegetables like nobody's business. Now, the hydroponics guys tell you that you CAN'T grow anything with nitrates below 100 ppm, and the aquaponics consultants tell you you can't grow with nitrates below 60 ppm. Unfortunately, this "knowledge" doesn't encompass the fact that these systems are growing vegetables as well or better than non-organic systems. If it works in the real world, it's impossible to argue with!

The ONLY time we ever see nitrite or nitrate measurements higher than these in an organic aquaponic system is during system startup. This fact piqued our interest, and helped us develop our current hypothesis, which may explain the difference between nutrient levels in our organic systems and in chemical-based systems (how we refer to systems that use hydroxides for pH adjusters). We think the chemical-based systems show these higher levels of nitrites and nitrates because the repeating applications of caustic chemicals used in them cause repeating die-offs of nitrifying bacteria, which then re-establish themselves in a cycle similar to the nitrite and nitrate spikes that happen during a normal aquaponic system startup. We'd love to try this hypothesis out, but we'd have to run one of our systems as a chemical-based system again to do so, and what would be the point? What farmer wants to get half as much for their non-organic vegetables?

The important thing about our discovery about nutrient levels in organic aquaponics is that it throws much of the conventional wisdom about aquaponics out the window. To be completely clear, we DON'T KNOW exactly what's happening in our systems. We would love to have a spectrometer, a lab, a year or two, and about $120,000 in salaries and costs for lab workers to get a good handle on what the actual processes are at a microbiological level. What we DO understand is that the systems keep growing stuff like crazy even though measurable nutrients are barely measurable, and they feed us.

And because to be human is to want at least an outline of an explanation of things, here's what we've come up with as a working hypothesis to explain this behavior:

The fish are in the system and are eating and pooping, so there is decaying organic matter in the water that is passing into the hydroponics troughs. The vegetables are still growing just fine, so they MUST be getting nutrients from somewhere. We think the small suspended bits of decaying organic material from the fish are getting caught on the plant roots, then decaying into ammonia right on the microsurface of the root, then the ammonia is getting metabolized into nitrites and then nitrates by bacteria that have colonized on the microsurface of the root. The nutrients then are immediately getting absorbed by the roots. There are no measurable nutrients or ammonia because all this is taking place in the few thousandths inches of microcosm around the multitudes of small roots of the plants, and there’s no way to measure ammonia, nitrites, and nitrates on a root without grinding it up and sending it off to an expensive lab for tests.

(Next week: "Some Incredibly Interesting Aquaponic Information"; this means we haven't got it figured out yet, but we will!)

Click to see our new Video!

Free Farm Tours
Aquaponics tour at the Friendly farm!

We hold a free workshop on our farm the FIRST Saturday of every month,  focused on growing food with aquaponics and permaculture.  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!


3-1/2 pound kalo (taro root) grown in a 2" net pot (little bump at bottom)


4-month old prawn (macrobrachium rosenbergii) grown in hydroponics troughs of our aquaponics systems

Special Offer! Sign up for our October 2011 Hawaii Commercial Aquaponics Training OR our September 2011 Florida Commercial Aquaponics Training (dates to be announced) now, and we will email you our Micro System package so you can begin studying aquaponics! ($99.95 value)

Sign up for Hawaii and Florida Commercial Aquaponics Training

In The Farmily
JackMicroSystemSmall 2
Jack's Micro System

Jack's Micro System was a victim of the same lettuce blight we talked about in the "Aloha" section this week. Because Jack hadn't planted a variety of seeds three weeks before we built his system so they had sprouted and were ready to put in the System right after startup (as the Manual suggests), the only thing we had available to put into his system was lettuce sprouts.

Jack and Mom immediately made a seed order for all kinds of things, which have  arrived and have been sprouted; they'll be big enough to put in the system in another two weeks.

Unfortunately, we'd planned to run lettuce in his system until these were ready, and because of the blight, we don't have any uninfected sprouts to put into the system. So, we won't have any plants to put in his system for another couple of weeks. And this raises a good aquaponics question:

"Won't the ammonia, nitrites, and nitrates build up in the system without any plants to take them out of the water?"

Yes, they would, IF Jack kept feeding his fish normally (as if there were a full complement of plants in the rafts). However, it is easy to keep these nutrients in the system from spiking dengerously simply by feeding the fish LESS.

If this kind of a situation happens to you, simply feed the fish about one-fifth of what you normally feed them, check the ammonia every couple of days to make sure it doesn't get over 3 ppm, and you should be OK. At the worst, you will need to dump system trough water and refill to dilute the ammonia level to below 3 ppm, until you have plants to put in the rafts.

The fish won't LIKE it, but we have kept tilapia in aquaponics systems for up to 3-1/2 weeks with no feeding whatsoever; they'll be OK.

We'll follow Jack's adventures with his new Micro System for the next few "In The Farmily" columns!

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