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Friendly Aquaponics Newsletter
Number 77
April 12th,  2012
Images from our farmily aquaponics farm
Aloha Friend,

Today is about the stuff that's plugged our water pump intakes in the past. It may seem silly, but we lost $10,000 once due to a plugged pump intake.

We'd measured and remeasured everything in the system in question, and were baffled, for it all tested out OK. We didn't understand until we did a flow rate test on the troughs, and found almost no flow in two out of four large trough circuits.

Ten thousand dollars is not silly, and our "antennae" are now on alert for similar situations. We catch them now before they cost us money. In today's newsletter and the next, we'll tell you about several such so you don't have to figure them out the hard way.

If you're interested in learning about our Solar Greenhouse technology, please take a look at our Aquaponic Solar Greenhouse Training (Special Offer in right sidebar of this email), where you will learn more about how to grow affordably using aquaponics in greenhouses than you can anywhere else in the world. The next training is in Hawaii in June 2012. 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 or IBC totes, 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 also cover how to make aquaponics systems out of weird things like old refrigerators and door frames; this makes aquaponics much more economical to get started in!

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 #77:
Pump Intake Filters, Part 1

The $10,000 plugged pump

Our $10,000 problem was an easy one to solve, once we'd figured out we had a flow rate problem. We had 7 gallons a minute coming out of a pump that should have been putting out 35.

How do you figure your flow rate? Easy: take a five-gallon bucket and stick it under the inflow fitting. We put ours under the trough inflow fitting, right inside the trough. Time it with a stopwatch, phone, or pocket timer, and see how long it takes to fill up the bucket. Then you do your math: if it fills the bucket in a minute, that is a flow rate of 5 gallons a minute. If it fills the bucket in two minutes, that is a flow rate of 2-1/2 gallons a minute. We've found for our 4-foot wide, 10 to 12 inch deep troughs, a flow rate of 5 gallons a minute in each trough is conservatively plenty.

Why was the flow rate so poor? It had been fine a year previously when I finished the system. When I'd installed the 2,000-gallon sump tank for that system, I knew I was going to put a couple hundred pounds of two to three pound fish into it (we use all our sump tanks as "real estate" to house fish; this means our main fish tank doesn't need to be as large). This sump tank had a 2-inch PVC intake that went to the pump, and these big fish couldn't get stuck in it, so I omitted the usual intake filter to "save a little time" (I saved ten minutes and $5 worth of parts).

Over the next several months, some 2-inch net pots came into the sump tank from the troughs, floated around, then fit perfectly into the 2-inch PVC pump intake line to the pump. Some plastic plant tags followed, and about month 8, the pump intake was so covered with solid plastic that it was pumping one-fifth the water it should have. We lost $10,000 due to poor plant growth that in turn was due to a poor water flow rate through the troughs over the next four months.

The fix was easy: turn the pump off, clean the junk out, then spend ten minutes making the filter I should have made in the first place. We haven't had a problem with that pump in the last year and a half.

The Right Filter Mesh Size

Your pump filter needs to have the correct filter mesh size for the "stuff" you're trying to filter out, for you can only let stuff through to the pump that the pump can "chew up" and spit out the other side without getting clogged. Generally, the smaller the pump, the smaller the mesh needs to be, and the larger the pump, the larger the mesh can be. For our 35 gpm 170 watt pumps with 1-1/2 inch fittings, we use 1/8 inch or 1/4 inch mesh for the filter screen. Here's some examples of the right and wrong size filter screens:

Both of these are "wrong" sized filter screens (2" net pot for scale). The 1/2" mesh on the right let grass stems through over several months that finally clogged the pump and cut flow to nothing; when it was replaced with the 1/16" mesh on the left, vermiculite, dead gammarus, and sludge clogged and collapsed it within about two weeks, also cutting flow to nothing. The correct filter size mesh for this application is shown in the next photo.

The correctly sized 1/8" mesh for this application is shown installed on the filter at the bottom; the too-large 1/2 inch mesh filter is shown at the top, along with a flat piece of both sizes of mesh, and a piece of 1/16" too-small mesh next to the net pot in the middle. There's a piece of stiff 1/2" mesh inside the 1/8" mesh on the filter at the bottom to provide a "backbone" to keep the 1/8" mesh from just folding over. You should still check and clean this filter every three or four months or so to make certain you have good flow rates in your troughs.

GrownOut1medium 2

Friendly Aquaponic's FIRST Aquaponic Solar Greenhouse in full bloom, Honoka'a, Hawaii, March 2012, (on a grey rainy day) showing PV panels, growing plants, and the mysterious Verticalis in the center!

(Next week: Part 2, Instructions and photos showing how to make these filters, and more info on how to keep your aquaponic water flowing freely. Thanks for listening!).

Click Here To See Our New Aquaponics Video!
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Purchase Trough Liner Directly From Manufacturer!

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 June 27-28th Aquaponic Solar Greenhouse Training, and receive a free Micro System DIY package so you can begin studying aquaponics! ($99.95 value)

More Information on Hawaii Aquaponic Solar Greenhouse Training

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