Backyard Aquaponics
A place to discuss aquaponics

Found this this morning:

http://www.thefishsite.com/articles/con ... arison.pdf

I don't want to make any comments to prejudice your thoughts before reading.

Some very impressive numbers... What a tragedy that those facilities are gone. I fear we need to recruit much younger folk, so the systems have a chance to expand.

I'd love to get Dylan Ratigan involved... he's using hydroponics- but employing vets... and supplying a good yield, I understand.
He could do oooooodles better, if he'd switch, eh?

I don't want to comment until we have heard from at least Rup and Ryan.

I think it's a load. He didnt invent flood and drain...Funny thing is that James built A big F&D system at UVI in the early 80s...82 I believe b/c we joked that it was the same year I was born...and went to DWC because their trial and errors led them to that development.

I also know the owner of the largest F&D ap system in the world (over an acre of bed area) and he is looking at converting to raft culture...


Everyones an expert.

An acre!

What problems did he have?
Why is he considering/going to convert?

Temperature problems (surface media acting as major heat sink), solids build up, tapered off/slowed growth, deficiencies, excessive labor planting and harvesting, HUGE area for sump which he want to grow fish in, several other factors.

The thing I found was that the numbers were not that impressive.

Out of the FnD system 2808 kg of fish from a food conversion ratio of 1.7. ie 4774kg of food in to produce only 15600kg or in other words 1:3.3.

My number crunching on the UVI Saudi systems gives a ratio of between 1:2.5 to 4.2.

Considering that Tom Sp claimed a result of 1:7 and some of the Scandinavian researchers and Ryan are claiming values of 1:10 I'm not impressed by 1:3.3.

I've never heard that Tom Sp copied his system from this Mark guys work but that doesn't mean he wasn't at least inspired by his research.

Since he is moving out of using them are you free to give details? Even contact details so I can speak to him myself?

Temperature I can really understand.

Solids build up: Can you tell us his stocking/feeding ratios to GB volume and design.

Deficiencies: I don't know why this should be any more of a problem than in any other system unless the media was reactive and the pH was causing nutrient lock out.

Excessive labour could be an issue depending on the crop. If growing salad greens then of course. If growing tomatoes why would the labour be more than the labour in a hanging gutter system?

Sump size would be design dependent.

Other factors?

Haven't read the article yet... but first thoughts... published 2013... definitely new...

McMurtry.... definitely worth a read... didn't know he was still doing research...

Bevan Suits... oh bugger... run away....

Without having read it... is it an actual recent study... or Suits interpretation of some old McMurtry data...

If the latter... just ignore it...

I'll go read it anyway....

Ok... appears to be an article by Bevan Suits... promoting his own interpretation of some of McMurtry's data...

Couldn't find any published reference to the actual spreadsheet attributed to McMurtry...

Indeed, couldn't even find a reference to the term "Integrated AquaVegeculture System"... attributable to McMurtry...

Suits, a long time advocate of McMurtry (no criticism attached)... is citing works from the 1990's...

And making statements without actual comparisons being made/available.... many of which are either wrong, or wildly wrong IMO...

Particularly in relation to comparative costings.. infrastructure build, and operating costs....

As to the yield figures reported.... I'd like to see the actual research paper data that backs his claims... if they actually exist...

You can see references to Bevan in posts on the forum going back to 2010... when he published an aquaponics e-book....

And you can see the sum total of his actual aquaponics experience on his facebook page.... https://www.facebook.com/bevan.suits/me ... 828&type=3

I wouldn't give the article any credence what so ever.... IMO...

If you really think Suits has the answer... you can invest in his methodology...

The numbers look so good... I'm surprised he hasn't built one himself...

http://media.wix.com/ugd/104b98_a2838d7 ... rGuide.pdf

Really? I thought the numbers were crap. That pdf quotes all sorts of numbers but the ones that get me are the ones that are no good.

For example 1 to 2 lbs for sq ft per month. Based on Cornell Lettuce production guide you can get 1.71kg/sq ft/month on an average growout cycle of 8 weeks in standard DWC hydro. So 1 to 2 doesn't sound impressive.

Plus who would grow salad greens commercially in a GB?

I can see good arguments for long term crops (tomatoes, capsicum, viney things, etc.) but the materials handling advantages of DWC or rolling NFT tables win hands down for commercial short term crops. Unless maybe they are cut and allowed to regrow?

Also who are you going to get to pay $1.17 a head for lettuce?

I was being ironic...

And I don't believe the numbers...