Aquaponics "Mythconceptions"

[GaryD]

Hi,

The following is a response to comments received from Dr Wilson Lennard about a blog post that I made.

I've addressed the comments in this thread because the formatting features of the forum make it easier to do so.

Hi,

Just a comment about your article which does cite my name and an apparent argument I make for using the gravel bed in a backyard aquaponic system as a mineralisation filter. As always in media, when things are taken out of context or not completely included, then the argument required by the writer is supported. In this case, my name (and that of my close friends and collegues) has been used in the context of being an "advocate for leaving solids in backyard systems".

If you could spare the time to read the post again, you will see that I did not suggest you were an “advocate for leaving solids in backyard systems.” Quite the contrary. I was suggesting that you (like me) favoured the removal of solids from gravel systems.

What is sadly left out here is the fact that I also advocate that backyard systems are configured correctly in terms of fish to plant ratio's. If this was the case (which it isn't at all!; EVERY backyard aquaponic system I have ever seen, whether home built or purchased from a supplier, has the WRONG fish to plant ratio's employed - please note that I use "FISH to PLANT ratio", which is not "system volume ratios" or any similar erroneous ratio!) then we would have far fewer fish in systems than we do now, and then, the chance of "overwhelming" the gravel bed with solids would be far lower.

Since you’ve misread my original statements there’s little I can say except that I accept what you say about the “fish to plant ratio” as being logical enough.......and I share your concern about system volume ratios.

I read a statement in an article that you wrote which reads….

“Research conducted at Melbourne’s RMIT University suggests that, for 1 Kg of Murray Cod standing biomass, 20 – 25 Green Oak variety lettuce plants are required to balance system nitrate concentrations.”

Is this the sort of thing that you’re talking about?

I can see how the fish to plant ratio approach would be most useful in a commercial situation. Can it be easily applied to backyard aquaponics where there is likely to be a variety of different plants in a grow bed?

Anyway, your SYMBIOPONICStm approach sound interesting and I’d be interested to learn more.

The gravel bed WILL mineralise solids at acceptable rates without impacting on dissolved oxygen, biofiltration etc...in systems. BUT, if the amount of solids entering the system is too high (most likely due to the wrong fish to plant ratio being employed and the subsequent excess release of solid fish waste) then yes, the bed will be overwhelmed with solids. Therefore, gravel beds will mineralise solid fish wastes at acceptable rates IF the system is designed with the correct fish to plant ratio in mind. What happens mostly is that the fish to plant ratio is incorrect, so too many fish inhabit the system, and subsequently, too much solid waste enters the gravel bed.

I agree with you that gravel beds will mineralise solids. My central point is that they will function even more effectively if the solids are removed and processed externally – with the nutrients being added back into the system.

In addition, I have NEVER said "...up to 75% of the solids in an aquaponics system may be in solution." What I have said is that up to 75% of the wastes produced by the fish in the system are in the dissolved form, because they dissolve directly into the water across the fish gills, OR, up to 75% of the nutrients in the water are in dissolved form. This may seem a trivial reading of what you have said, and it may even seem pedantic. BUT, the fact is that the statement "...up to 75% of the solids in an aquaponics system may be in solution." is completely factually different from what I have ever said!

You were correct – I misunderstood what you wrote. On reviewing the source of the material I can see that I interpreted the term “waste” as being solids rather than applying to all waste (including ammonia emanating from the gills) coming from the fish.

I don’t believe that your concern is trivial or pedantic – and, while it doesn’t alter my main contention, I’m entirely comfortable with you pointing out the error of fact.

So, I am not against the information you are supplying to the public; much of what you have to say seems based in reality and uses common sense. In addition, there is much (but not ALL) that I agree with.

I’d be happy for you to speak about those specific things that feel you cannot agree with.

However, if using peoples names to make arguments, it would be nice to stay true to that persons beliefs and NOT to use that persons name, and more importantly, your interpretation of what they may have said, as an argument to support your own thoughts or feelings.

As I’ve already pointed out, your original concern is the consequence of your misreading what I wrote…….and I’ve addressed the error of fact. If you have further concerns, I’d be happy to hear about them.

Thanks for your time,

Thank you for your time. I hope that my response does something to address your concerns and that you feel inclined to let us know more about how SYMBIOPONICS works.


Gary Donaldson

[damien little]

is "mythconceptions" the way people with a lisp say "misconceptions"?

[GaryD]

Um.......Yeth.

[GaryD]

Hi,

On 10th November, BYAP's Joel Malcolm made a post on a thread called Solids removal - how and why?

This was a significant post and is worthy of further scrutiny.....

I don't remove solids from my systems, except for the large floating raft system where the larger solid matter is broken down outside of the main water flow. If you're having troubles with solid build up in your beds then you have too many fish, or preferably not enough beds and as such plants.

No suprises there......Joel is a fundamentalist when it comes to flood and drain grow beds. I'm sure he wouldn't be too offended if I said that he liked the simplicity of the standard recirculating Speraneo-style aquaponics system and he's promoted its use for some years now.

I do think Joel is a bit limited in his assessment of the options. If you're having trouble with solids you can also remove them and/or consider an open loop plant growing regime that can accommodate water with a high solids loading.

One of the biggest input expenses for a system is fish feed, one of the biggest outputs from a system are the plant crops.

Yep......most people would agree with that.

By my way of thinking you're better keeping the fish stocking levels lower and making complete use of the feed going into the system, as well as the wastes from the fish.

This is the interesting bit. This is not the first time that Joel has referred to low stocking densities as being the secret to making a standard flood and drain aquaponics system work.

In fact, I'd go so far as to say that it's the only way that they can be made to work......and that assumes a 2:1 (or greater) grow bed to fish tank volume, plenty of aeration and a fish species that is not too fussy about water quality.

If you're chasing high stocking levels of fish, then to push your levels higher you will need to remove solids, and this brings about complications, inefficiencies and more work.

The need to remove solids for anything other than low stocking levels is pretty much what I've been saying from day one. It's interesting to see that Joel is now starting to take a similar line.

Where Joel and I might part company on this one, however, is the bit about "complications, inefficiencies and more work."

Good system design will address the solids problem and you'll end up with an aquaponics unit which is far more efficient than a standard system.....and you'll be handsomely rewarded for any small additional effort with more fish, healthier plants and a more cost effective operation.

For my money I'd go with less fish and no solids removals every time. I know that some people love to have lots of fish, but I'm happier to go with a simpler balance.

If you're not concerned about getting a return on your investment in your system (assuming you laid out the big bucks that it takes to put a reasonable - 2,000+ litre fish tank/four to six grow bed - kit system)......or you managed to cobble your system together out of recycled components for little outlay......you may also choose to go the "simple" route.

Even then, your power bill may make those vegetables and a few fish pretty expensive by the time they get to your plate. Remember, it costs the same to pump water regardless of whether the fish tank has no fish or many fish.

If your main game is growing organic vegetables, there are much surer and cheaper ways of doing it than running an a lightly-stocked aquaponics system.

Gary

[Dufflight]

This is still an Aquaponics Forum. Or did it change to a diss AP or people in AP at any chance. If so I didn't get the memo. And a forum name change is in order.

[GaryD]

Hi,

I'm not sure how you arrived at the "diss" (what is that anyway?) bit about AP or people.

What this forum is about is discussing ideas related to food production. It's not essential that people agree with each other. In fact, in the interests of objectivity and advancing the discipline of aquaponics, it's a good thing that people challenge ideas.

As I demonstrated through my "mythconceptions" blog posts, there are good reasons for closer scrutiny of some of the ideas that attend aquaponics.

I've spent some years challenging some of the fondly held (but fundamentally flawed) ideas about things like solids removal and grow bed depth, and it seems that a different view of the world of aquaponics is finally beginning to gain traction.

While most people to whom I talk seem comfortable with that, all it seems to have produced from the architects of some of the mythconceptions (or their sycophants) are personalised rants.

There are no secret cows on this forum......and, unlike some other forums, no-one gets bullied or locked out of here for taking a contrary point of view on any aquaponics or food production-related issue.

Got anything technical to contribute to the discussion?


Gary

[Dufflight]

Its the fundamentally flawed bit. Most of these Mythconceptions you are talking about are general rules for beginners to help minimize the failure rate of new systems. Bit like training wheels or speed limits for learner drivers. We can all push the boundaries once we have a firm grip on AP but I don't think its wise to throw a kid on a bike for the first time without help or to tell a learner driver to go as fast as they like. I don't think telling beginers to use shallow GB's is a good idea. When they have trouble growing things or are under filtered we will have to tell them to add more media. But if they have allready cut there GB's to a lower height we will have to tell them to get new ones. And there is still no working model to base this on any way.

And diss is a short version of disrespect. This is the only forum to my knowledge to have a PHD politely tell them to stop using there name.

[GaryD]

Hi,

This is the only forum to my knowledge to have a PHD politely tell them to stop using there name.

While that's not quite how it happened, is it possible that this is the only forum that is capable of capturing the attention of someone with that sort of background?

In allowing yourself to be used to fire other people's bullets, I hope you're taking the time to reflect on the irony that this is the only forum that would allow for that. I keep reminding myself that, while you are provocative (in a personal sense), you are acting at the behest of others who would like to do what you do but lack the courage.

Have you thought of anything new of a technical nature to bring to the discussion?

Gary

[Dufflight]

Other people's bullets. These are my views and I don't speak on anyones behalf but myself.

Nothing new of a technical nature until new toys get here.

[GaryD]

Nothing new of a technical nature until new toys get here.

Love toys......what's on your list?