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Comment by Jacques L. on January 1, 2014 at 10:36pm

Ahhh!!! The Holidays!

Good times... a few extra days can do wonders for the soul ;)

I've been fairly lax in my expansion plans for my AP... but thankfully I've had time to remedy that as of late.

Gonna double my grow bed capacity, and just wrapped up the framing on 2 new beds, which will give me an additional 48sf of grow space!

Yay!!!

Details may be viewed here: 

http://bit.ly/19KQRRQ

Comment by Kim Romen on January 1, 2014 at 9:42pm

Kris, good to know.  thx!

Comment by Kim Romen on January 1, 2014 at 9:40pm

Dr. Brooks, Thankyou for the charts!  With those charts it seems we are getting nutrients at a ph of 8, so that's good, but shooting closer to a 7 makes sense if that off-sets any possible negative affects of possibly consuming acid.  My original intent of doing AP was to eat more organic.  I'm thinking this would not count as organic if we are putting pool acid in the system (and feeding fish non-organic feed as well, ofcourse). 

Are you aware of typical acidity of ammended AZ soil and the likely nutrient value of food that is bought in the grocery store.  I guess there'd be other factors to take into account like time  food took to get from farm to stor to home, if it's organic, and if the AP system had other means of nutrients added like worms or worm compost tea.  

Anyone's thoughts on the nutrient value of gardening in AP with a high PH level as compared to buying from the grocery store is welcome. 

thankyou!

Comment by Kris Pauly on January 1, 2014 at 7:27pm

@ Kim - We use a 60/40 coir and vermiculite mix for sprouting and in our system.  works really well for us.  both raft and flood and drain.  I hope that helps.

Comment by Dr. George B. Brooks, Jr. on January 1, 2014 at 2:55pm

Happy new year Kim. I have seen a number of different charts, none are perfect.  The following two however present data that is somewhat close to to what I have seen.

Comment by Kim Romen on January 1, 2014 at 12:21pm

PH-i'm looking back at old posts.  I haven't messed with the PH yet since the system seems to be doing fine and things are growing.  I've harvested a few zucchini, tomatoes, there is plenty of lettuce, radishes...  My thinking is often times "if it's not broken don't fix it" so I haven't added acid to the system.  I've seen it said that veggies don't absorb any nutrients if the Ph isn't right.  I'd think they're absorbing some nutrients since trying to clone in plain water produces very little, but I am able to produce much in my AP system.  As far as not absorbing the full amount to get the highest nutrient value, have there been studies on Ph and levels of nutrients the plants absorb?  I wonder if there are other varying factors as well such as algae in the system, fish/plant ratio...

Also, does anyone know if there have there been studies on the nutrient value of plants fed by natural sunlight verses artificial lighting?

thankyou and Happy New Year!

Comment by Kim Romen on January 1, 2014 at 11:45am

anyone grow in coco-coir as the media in their system?  Gardenpool does this and I wanted help considering +s and -s. 

plus that I can see:

1. light weight

2. easy to dig through

3. holds moisture

4. could probably grow root veggies and have them look as we know them

minus:

1. cost

2. would it get stuck in the bell siphon/pump/get into the fishtank.../depends on the kind of system ofcourse...?

3. someone said good bacteria doesn't readily grow in coco-coir?

Dennis/gardenpool said u'd clean it like any other media.

thx  :)

Comment by Bob Campbell on December 30, 2013 at 9:08pm

@Dr. Brooks - I used weed tea for awhile and found that it too works well as a nitrogen source.  But it's more work than pissing in my sump so I gave it up.  But if you are squeamish about pee then age it or use weeds. 

What I did was soak weeds in a barrel of water for a couple months.  That may be  longer than necessary but it leached the nutrients out, and I had a lot of FREE nitrogen for the garden.

Comment by Dr. George B. Brooks, Jr. on December 30, 2013 at 6:35pm

Part 2

A couple of last things regarding overfeeding and “pee (ugh) ponics” to consider. Overfeeding kills, often because excess food fouls the water buy creating excess bacterial growth. Some of the bacteria can attack the fish directly as in fin rot. Others may release toxins in the water or are toxic in general. Other serve as food for protozoans, which then proliferate and foul the fish’s gills or damage the fish directly as they feed on bacteria coating the fish as with trichodina etc. Fish max or plant max, the health of your fish continues to be important. As I teach my students, manage to the maximum benefit of all species in the system and you will get the best result.”

Pee-ponics to me is troublesome not only because of the “yuck” factor but also because of pathogens. Human urine is normally sterile. However we don’t know when we have a minor infection that you are now introducing directly into your system. Even if they don’t grow and go dormant, they are still there when they did not need to be. For these reasons and more it also breaks every food safety rule in the book. Though we are working to get the authorities to write food safety rules to accommodate aquaponics, I predict this practice they would have a great deal of problem with. To me, the risk is not worth it.

Finally there is the self sufficiency angle. Aquaponics is a unique opportunity to provide a nearly self sufficient complete low cost human diet within a confined space. Three of the major issues that remain are that the systems are usually constructed out of plastic, the need for energy and non-sustainable fish food. Better and better solar panels and batteries will solve the energy problem and some fish like tilapia can eat plant wastes and so thrive in that manner. The plastic tanks remain a problem. However all in all and in particular for low income communities even here in Phoenix, aquaponic production particularly fish protein has the potential of addressing many local nutrition problems as well as the associated nutrition based pathologies like obesity and diabetes. 

Again, a most detailed and interesting response. Thanks ;-)

 

Comment by Dr. George B. Brooks, Jr. on December 30, 2013 at 6:24pm

Part 1.

Hey Bob. Thanks for a GREAT response!!!! I agree with much of your intent. However I do have a different perspective to share on the same information. To begin, aquaponics is aquaculture.

From my experience aquaculture is not as black and white as you suggest. In the world that I work, the definition of aquaculture is “the farming and husbandry of aquatic animals and plants.” Therefore for me and most of the folks I work with, aquaponics is an advanced form of RAS aquaculture:

RAS (Recirculating Aquaculture Systems)

From this point, there are two basic directions that aquaponics is moving:

A. Fish max (my terminology): Where one seeks to maximize the pounds of fish one can produce on the minimum number of plants.

B. Plant max: Where one seeks to maximize the number of plants you can produce with the minimum number of fish. (Your excellent response speaks mostly to this side of the equation)

In my work in aquaculture and urban sustainability, aquaponics is a holy grail. In the past it was extremely difficult to grow fish in urban areas because of the cost for biofiltration of the water. Even if you could do this successfully, you still had to dump the water after a while due to nitrate buildup. However in RAS – ponics as some engineers were calling aquaponics last year, the mechanical biofilter has been replaced by mechanically simple “constructed wetland” filtration beds where marketable plants instead of cattails remove the nitrate and enhance the biofiltration. All in all the significant increase in economies of scope aquaponics provides (as you suggest) drives the cost of the individual products down while eliminating most of the waste water and requiring much less energy.

Aquaculture is aquaculture, biology is biology and engineering is engineering. The old principles are the foundation that everything else is built on. As with any aquaculture system, you adjust your management practices to meet the needs of your system and the market. The same is true for this new version of RAS. When we replaced the mechanical biofilter with a constructed mini-wetland, we had to adjust our management processes accordingly.  The use of salt, UV. ozone ect are simply management tools to be used when appropriate not aquaculture requirements. The results so far have been good and still improving. 

Your section on energetics is pretty good and I mostly agree. In particular regarding the fish food. However more and more fish food is now formulated with plant proteins. Doing so reduces or eliminates the need to harvest fish from the ocean to turn in to pelleted fish food later. This work is going pretty well for fish that feed on the lower trophic scale like tilapia. The farther up the scale you go, the more difficult it gets. I agree there is still much work to do here but the work is indeed getting done. Secondly there is an interesting concept called IMTA (Integrated Multi-Trophic Aquaculture) that shows promise in further reducing food costs through increasing efficiencies and sustainability, at least for tilapia and like fish.

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