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Friendly Aquaponics Newsletter
Number 34
April 13th,  2011
Images from our farmily aquaponics farm
Aloha Friend,
We'd only just returned from the first mainland Friendly Aquaponics Affiliate training when we discovered yet another way to foul up an aquaponics system! We don't experiment with our commercial systems because they're our bread and butter, but frequently learn things by accident. Here's an example:

When we installed the sump tank for our system #3, I didn't spend the 20 minutes necessary to build and install an intake filter for the water pump (inside the tank) because I KNEW the fish going inside that tank to live were all 1-1/2 to 2 pounds, and none of them would fit inside the 2" PVC pipe that is the pump intake. I told myself I would build this filter LATER (a dangerous word when used in conjunction with aquaponics).

Now it is months later. We only notice the poor growth in system 3 after two weeks, because it came on slowly. Susanne noticed this right away and asked me to check the flow rates. I was busy and stupid and waited quite a while before doing it. When I finally checked flow rates coming into the different trough circuits, they were abysmally low. One trough only had 1/3 of a gallon per minute coming into it; less than our WaterPik puts out! So I opened up the pump impeller housings and found several 2" net pots plus some of those flat white plastic plant tagging stakes in there, almost completely cutting off the water flow into the pump.

Because net pots (left to their own devices) will only float up to a standpipe in a trough and gently bump the outside without jumping up over the edge and down into the pipe, we deduced that someone (probably a small innocent child) had dropped the net pots down one of the trough standpipes, where next stop was the sump tank. They floated in the sump tank for awhile before going neatly into the 2" PVC water pump intake, thence to clog both pump intake pipes almost solidly when the plastic plant stakes floated in on top of them. After cleaning out the mess (which took hours of disassembling and reassembling pumps to do) I spent  20 minutes building and installing a filter on the pump intake.

The production we lost because of the poor water flow rate into the troughs cost us around $7,000. We came to a conclusion: There Is NO "Later" In Aquaponics!!". If you notice something is not right, do your best to FIX IT NOW!

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 #34:
Nutrient and pH Levels In Organic Aquaponics Systems
(Part 1)

The nitrifying bacteria which convert ammonia to nitrites and nitrites to nitrates live all throughout the system, including in the water column. They live in the troughs, in the water, on the undersides of the rafts, on the liner, and most importantly, on the plant roots themselves. You will notice the fish tank has a roof or shade cover specified; and that we always want to have rafts on the troughs, even when the rafts are empty. This is because the nitrifying bacteria are photo-sensitive and will die if exposed to too much light. Also, if you let too much light into your system you will be growing algae instead of bacteria and wasting your nutrients on these "useless" vegetables. When you have algae instead of bacteria, the algae use system nutrients, add excess unwanted ammonia to the system when they die and decay at the bottom of the troughs. This decay process also depletes system oxygen, and a resulting low DO may stress the fish. Just keep everything reasonably covered without being too obsessive about it, and you'll be fine.

We learned (in the excellent 2007 UVI aquaponics course), that aquaponics systems tend to become acidic (lower pH numbers) over time because of the conversion of the carbon dioxide the fish breathe out into carbonic acid; and that the operator needs to add bases to the system (chemicals with higher pH numbers) to bring the pH back up into the range that is good for fish and plants.

The first six months we operated our original UVI-type systems, we did so EXACTLY as we had learned, by adjusting pH with potassium hydroxide and calcium hydroxide (chemicals that are very basic), when the pH went down below 6 or so. This was NOT an organic system, because both of these chemicals are on the OMRI (Organic Materials Research Institute) Not Approved list.

These two chemicals are also quite caustic; if you scoop up a handful of potassium hydroxide (lye) without a rubber glove on, you will have a serious chemical burn to deal with. Although UVI told us they adjusted pH about once a month, we found that we had to adjust pH every two weeks at times. We did so VERY carefully, because if we put too much of the hydroxides in, we could cause the system pH to hit levels that would damage or kill fish and plants. Our method was to put in a small amount, let the system circulate for 24 hours, then remeasure pH, and adjust again (carefully!), if we hadn't hit our target of 7.0. Because this was so new to us, we took water quality measurements twice a day for four months, going through a mountain of test strips. We have a very good picture of temperature, pH, DO, ammonia, nitrites, and nitrate levels in the system during this time.

When Susanne was preparing for our organic certification in 2008, she got rid of the potassium and calcium hydroxides and substituted calcium carbonate to adjust our system's pH. In Hawaii, calcium carbonate is coral sand from the beach, AND it is on OMRI's approved list. We can tell you there's nothing safer; because our kids used to eat beach sand when they were little and it would show up in their diaper the next day. Anyway, we put a few handfuls of calcium carbonate in our systems the next time the pH went down to 6, and the pH went up to 7.0, just as it had when we were using the hydroxides.

Calcium carbonate (coral sand), is not only a milder base, but is also a buffer. Buffers are chemicals that will go into solution, but only to a certain extent. In other words, if you put two cups of a buffer into a system, but it only needed one cup to get to a pH of 7.0, then the other cup’s worth will simply lie on the bottom of a fish tank or trough until the pH drops again. At that point, the buffer will slowly and constantly re-dissolve back into solution in the system water, stabilizing and keeping the pH constant, until all the available buffer in a system has been used up and the pH drops again. Now, you need to add more buffer to the system.

What surprised us out of our slippers (this is Hawaii, remember?) was that after a month the pH was still 7.0! Even more surprising, it was still 7.0 after THREE months of no calcium carbonate additions! After four months, the pH was down around 6.4 and we added calcium carbonate again. This time it was six months until we saw the pH go below 6.90, and we adjusted when pH hit 6.7 at seven months or so after the last addition. This was the LAST time we adjusted pH in any of our systems, TWO YEARS AGO! The pH has been rock-steady between 6.9 and 7.1 for two years, in all seven of our systems. This was pretty interesting stuff!

On farm tours now, I ask if anyone present is a hydroponics grower, and usually get several hands up because aquaponics attracts hydroponics people looking for a better way to grow. Then, 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 between 6.9 and 7.1? Someone will often start to take the bet, then think better of it and say "you wouldn't make a bet like that without inside information". It's true, I wouldn't, but then I KNOW from years of experience that it's a safe bet; pH is rock-steady in organic aquaponics systems. The aquaponics "experts" don't have a clue why, because they've never operated one. We'll explain why next week.

Even more interesting is what happened with the nutrients in our systems. Before we went organic, we would get system nitrite measurements ranging from 0.5 to 4 ppm, and nitrates ranging from 20 to 200 ppm. About two months after we went organic, nitrites dropped to almost unmeasurable levels, and nitrates ranged from 3 to 10 ppm! We went into shock for a few days, and only gradually came out as we realized that things were growing as well as they ever had, if not perhaps better. We purchased a TDS meter recently and measured these same systems; they measured from 82 to 120 ppm TDS (Total Dissolved Solids), or basically pure water. To compare, the recommended strength of nutrient solution called “seedling strength” that growers start hydroponic plants in has a TDS of between 200-250 ppm, and "normal strength" for mature plants is usually 300-500 ppm.

Two years later, 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, it's impossible to argue with.

(Next week: "Nutrient and pH Levels In Organic Aquaponics Systems" Part 2, with MORE information on this topic).

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 April 4-7th, 2011 Hawaii Commercial Aquaponics Training OR our October 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 (9) and I (old as the hills) built Jack's Micro System this week. I had been promising Jack we'd do this for the better part of a year, so it was definitely a case of "the cobbler's children have no shoes". We cleared a plot of level land, staked down the weed mat over two layers of ripped-up junk plastic, and started assembling troughs and plumbing the system.

We put the 100-gallon horse water trough we're using for a fish tank in first, then situated the two troughs. Micro System troughs when fully assembled but with NO water in them only weigh about 45 pounds, and Jack and I each took a side of a trough and placed them easily and exactly where we wanted them to go.

Next, we connected the two troughs in the middle with a 1-1/2" PVC pipe that we ran on the surface between the troughs. Why not bury it? Well, it's just as easy to put a gravel or sand ramp on top of it after it's installed, to keep people from tripping over it. This is one of the big advantages of the Micro System: that you can build and operate it in the driveway of a rental house you don't own, then easily move it, the plants, and the fish to another location because you don't have to dig up buried pipes (not fun!). Try doing that with a soil garden in the backyard!

After placing the troughs, we plumbed in the water line from the far trough to the water pump, which we placed right next to the fish tank. Then we built a simple air pump house, installed the two Whisper 300 air pumps in it, and put air tubing and air stones with O-ring bumpers on them in the troughs and fish tank.

After all plumbing was done, we siphoned over about 450 gallons of water from a nearby biosecure (means no bad bugs, no bad fish, no bad crawfish, duckweed, etc) commercial aquaponics system, leak tested all water fittings and pump, checked airlines, planted sprouted plants in their net pots into the rafts, and Bingo! Jack had "Instant Aquaponics System!"

When we started, we didn't have much of a variety of seeds, so Jack planted lettuce (which we have LOTS of seeds for), and is planning a seed order for all the varieties he is going to try out in his new system! We'll follow Jack's adventures with his new Micro System for the next few "In The Farmily" columns!

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