Backyard Aquaponics
A place to discuss aquaponics

Stuart,

Given what you post concerning DO and Plant health in DWC, adding DO at the Fish tank makes even more sense.

The cost and long amortization of high end greenhouse real estate makes me want to avoid it like plague. Talk about sticker shock, $200 per M2....wow

Further to this, whilst these businesses look good on paper they are long contracts at low margins and may fall apart should significant problems rear their head.

The industry of commercial contract AP is so new none of the businesses that we know of are even out of their first year of contracted deliveries.

I will say the consistency and visual appeal of the produce I have seen at my local supermarket is brilliant. This is seriously impressive stuff, I am very impressed.

BUT

Someone putting on their armor should not brag like someone taking it off.

Compromises..no way. I want cheap, reliable, simple, productive, modular and expandable...if I have to build, design and construct it myself:-)

They wont give me the capital to do it my way so I wont be going into debt to do it their way. That means I have to begin on savings then expand on cash flow and profit alone, that suits me as, debt service is the true hell on earth.

Finally, if you can't put a baki shower or passive degassing box above your fishtank because of space constraints. You're in the wrong space....move.

I think this is the one you are talking about and its about half a hectare.

I've got a quote from these guys and a fair bit of info on the system but not how it is operated which didn't really give me the ability to asses the value as well as I would have liked.

Like I said it depends on so many factors. For example if your flow rate is high enough then you can afford to have your gas transfer in only one spot. If on the other hand your hydrualic retention time is high in the raft tanks (low turn over rate) then the oxygen may get used up faster than it is adequately replaced All depends.

On the other hand as the saturation goes below 75% then the efficiency of air stones starts to go up quite substantially. Which isn't to say they are the way people should go but merely that they could be.


Yes but we don't have any HP businesses that we can compare with AP for the production of leafy greens. The reason for this is that there are no new HP or lettuce operations with any published figures. Tomatoes and capsicums on the other hand are another matter entirely. Over the last two years there has been an influx of Dutch money and expertise into the HP fruit market (toms and caps mostly). The reason for this is that a lot of the Dutch production families have realised that they can invest their cash in Europe and get their money back and out in ten years. Whereas in Australia they are getting their money back in four years even with the margin pressure placed on them by the big two supermarkets.

Technology costs money but the rewards are huge. I don't know about you but I'd be happy to go into debt for 20mil at 15% or even 20% interest if I was getting a 25% ROI.


Not sure what you mean by this


I don't want to go that way but if I can't raise the capital for a system that has a decent economy of scale I will have to. To do so would mean I would have to economise on the economy of scale that I think is exceptable. I can make a system modular and while that will allow for organic growth the economies of scale are in the toilet. Also for a business to grow at some point it has to leap the canyon between a small scale direct market approach and a large scale mass market approach.


It all depends. I can fit 200t of fish production in less than 800m2 but that fish production will need at least 1ha of hydroponic growing area (based on a ratio of 1kg of fish food producing 5kg of plant production). That means that if all the aeration components are in the FT area then the furthest HP production area is a long way away. Which is one of the advantages of air pumps. Piping oxygen rich water in sufficient quantity to ensure enough oxygen in all areas of HP production is certainly possible but will take energy and/or large pipes to reduce friction losses. Air lines can transport much larger masses of Oxygen (in air) through much smaller pipes (less capital) to all parts of the facility.

What is most likely is that a combination of strategies will deliver the best results. If the plants don't care if the DO saturation goes below 75% 50% then there is no need to provide more oxygen than that to the plants which would make air delivered through diffusers a relatively efficient method of aeration. However while 75% saturation may be ok for plants it is not for most fish we would culture in Australia so it is there that more efficient methods of aeration could be employed to get the water saturated with oxygen

Just seeing the round HP system, has sparked so mamy ideas. Does a venturi style airation system fail at the commercial scale? I'm planning on it in my theoritical outdoor system.

Venturi style aeration fails at the backyard level, how can you expect it to work at the commercial level?

Yes, yes, yes. Oh so yes. Venturies for aeration make airstones look like the paragon of hyper efficiency.

If this was a backyard thread I'd be more gentle but since this is a commercial thread...

No I'll be good.

Stuart,

You make me sound anti air :-)

When it comes to O2 consumption, I think tidal growbeds will out perform DWC in Kgs of veggies grown. They may even come close to o2 neutral if water delivery,flows rates and retention times were ideal. ("ideal" is not the word I wanted to use but the right one is gone from my brain) To be truthful I really suspect that, overall, they add o2 to the system. Since it is BOD that removes o2 from the system I am at least technically correct, if not actually correct.

If saturation goes below seventy five percent your are not gonna have to worry about growbed o2 consumption with all the fresh fertilizer you just made coz the fish wont be pulling oxygen from the water anymore. They'll be dead. Under no circumstances would you or should you design a system that returns water below saturation to the fish tank.

Scale.

Overall system size is the factor that limits AP commercially... it just doesn't scale well. It's a great idea until you try to make it big then you get clobbered by plant costs, systemic limitations like flow control, water distribution, retention times, flexibility, robustness etc: All these disappear or a reduced by modularity. However, they only dissapear if you design cleverly and inexpensively.

Finance
This is a very technical subject but it is my opinion that banking and finance has become a monstrous crime scene. I have zero access to the books of these Dutch folk claiming 25% ROI's

/Snip/ Big rant on the GFC

But

Hey! 25% ROI... I'm surprised they aren't throwing money at us.

Space,

I'll stand by what I wrote. Seriously just move.

Venturies,

They work best at large differentials like you see in carburetors.

In high flow low pressure differential systems... not so much.
and high flow low pressure differential describes AP to a tee.

Stuart,
"Someone putting on their armor should not brag like someone taking it off."

It's a bible quote
It just means that actual performance may no be as advertised.

Depends on how you measure the comparison. If you were to plant to harvest density in GBs and the same density in rafts then quite possibly. If you were to vary the density in the rafts then not so much.


I would have said technically and actually correct.


I must not have explained myself very well. You use airstones to keep the DO above x% of saturation say 75% in the raft tanks. When the water goes from the raft tanks to the FT it could go through a bacci shower as you suggest so that when it exits the shower and enters the FT it is at or near as damm to 100% saturation.



I'm not sure I'd agree with that. A modular system tends to have higher capital costs and higher operational costs. Many lessons can be learnt from the AQ industry where capital costs and operational costs have been reduced by increasing tank sizes. Basically the limit on tank size becomes one of risk management with many operations heading to tank sizes that are just huge. Such large tanks are easier to manage, require less electricity to run and use less materials to construct.

One of the big criticisms I have of almost all AP "commercial" systems is the lack of knowledge and experience they have used or adopted from the AQ industry. So many systems based around tiny tanks that are so expensive. For example when you see AQ tanks used they are often around the 10kL size or less. Such tanks cost around $140/m3 (from polymaster) where as I can make relatively modest (by AQ standards) 41m3 tanks for $55/m3 (including labour). When you factor in the cost of plumbing multiple small tanks compared with one large tank the disparity between the cost per m3 of FT goes up even further. Same is true of GBs, Raft Tanks, Pumps everything. Which is why scale is so important.


Well I haven't seen the books either but as far as claims go I think it is pretty accurate. It came up in a disscussion about the boom in Glass House constructions over the last year and the Dutch guy started to explain why. He wasn't canvassing for investor or trying to drum up business. They had all the money they needed so they weren't asking for investment. Rather they were facing increasing problems finding skilled staff to operate the houses. To overcome this they were getting people in from the Netherlands and sending people from their Australian operations to work in their European operations for training stints.



Not familiar with that one. Verse? Reference?

MSA I have a vague recollection that venturi's are sometimes used in Commercial operations but its for O2 injection.

Yep, quite a bit but the guys at Aquasonic where not able to convince me it was a good idea. Especially when used with O2 cones.

The idea they were floating is that the venturi creates very fine bubbles of O2 that make the O2 dissolve better in the O2 Cone. However, since you can tune O2 cones so that they are 100% efficient I couldn't see the point of adding 4m or 5m or more to the Total dynamic head because of the restriction from the venturi.

Stuart,

I don't know how to use the full editor so your words will be in quotation marks and be followed by my thoughts on them.

"Depends on how you measure the comparison. If you were to plant to harvest density in GBs and the same density in rafts then quite possibly. If you were to vary the density in the rafts then not so much."

My preference comes from the idea that double handling anything is the epitome of bad design. Moving plants from one raft to another is not clever and the extra labor will eventually eat up any construction cost saving.

Even if I was using rafts...I would go for set and forget as a discretionary labor cost stretching into an infinite future will be a big number. Given the infinite future costs, I think I'd go for bigger beds and pay up front.

It's the same dynamic for DWC aeration as discretionary labor a cost stretching into infinity. it's just economic suicide. All these ongoing costs are a constant drain on the business' purse so, avoiding money sinks at the planning stage is a crucial business decisions.

"You use airstones to keep the DO above x% of saturation say 75% in the raft tanks"

What makes the DWC bubbles equation even more negative is that the aeration from surface agitation is lost because the surface is masked by the raft.

"I'm not sure I'd agree with that. A modular system tends to have higher capital costs and higher operational costs. Many lessons can be learnt from the AQ industry where capital costs and operational costs have been reduced by increasing tank sizes."

I do not dispute that ideas should be taken from aquaculture when appropriate.

This line of thought seems to have merit for someone wanting to go commercial but it's about choices. I've got no problem thinking big...I just can't afford it and when you self finance long ROI's are torturous. There are other reasons as well.

I've mentioned loss of flexibility and robustness before.

I think smaller cohorts at various states of turnaround is desirable at smaller scales.

Firstly, there is the 'all your eggs in one basket' argument because if disease or disaster strike, smaller cohorts reduce the gravity of such events.

Secondly, there's potential to have greater control over the nitrogen cycle and total nutrient levels for plants and fish.


The there is this:

The future is going to provide real value to the modular system designer with things like intelligent net workable feeders and probes plugged into control algorithms running on cheap tech. This is just a start. These combined with artificial intelligence and fish cams that could monitor fish behavior and feed back to operators is definitely in the future and if Moor's law applies they could become ubiquitous.

I think this last one is a little thin but if attained the sky is the limit. Technology is moving in my direction it's just getting cheaper and cheaper and better and better. Larger Aquaculture operators are already using predictive technologies to tailor feed ration rates and manipulate many system physical operations and water parameters.

"So many systems based around tiny tanks that are so expensive"

Not for me mate, I'm would use IBCs. They are perfect to my mind. For just $50/m3 they maximize space, they're tough, you can stack them, truck them around.... even with fish in them. Modular baby modular!

I think I may have got the wrong idea about the four year payback. I was thinking a 25% ROI but I think we might be talking about depreciation rates. If it's depreciation then I think the money has to come back as a rebate from tax owed which would mean you'd have to earn sufficient from the enterprise to pay enough tax to cover it. I'm not sure about this.

"Not familiar with that one. Verse? Reference?"

It's just not that important don't worry about it.

Terry

You don't move plants in DWC's (well sort of). In large operations you have a long trough with multiple rafts and they are moved up the trough as the plants grow. This is to ensure you are continually cropping, or to put it another way your income stream is constant and you can supply your market with a consistent supply of produce (its like a conveyor belt).

IBC's for a backyard system are ok but not ideal (they are relatively cheap) go really small or fairly large say 15kl the way a backyard system works is neither economic or sensible. This is only imho.

Sleepe,

Yeah I was thinking of raft systems where tighter spacing are used initially and then the plants are removed to final spacings. In this instance it's not the rafts being used that I don't like, rather the labor to move them from initial to final spacing. If I chose to use rafts I would place seedling in their final spacing immediately and avoid the extra labor.

The choice for IBCs was initially made on price but as my ideas have progressed I am beginning to see ways of using them that will really compliment my design. It is no secret I like modular designs and I design to take advantage of the IBC strong points and limit the downsides.


As I thought about growing this hypothetical business I thought about adding a dedicated fish room. I came to the same conclusions but for slightly different reasons...IBCs are the way to go.

This centered largely around packaging the dedicated fish systems within well insulated shipping containers. The IBC and the shipping container just work well together.

When using IBCs you can think about forklifting IBCs of fish from inside containers to inside green houses seasonally. Nothing in the Aquaculture world offers this level of flexibility.

I'm sorry, why do you want to forklift around your fish tanks? So you can have more plumbing lying around waiting for a workers comp claim? No offense, but few tanks in the "Aquaculture world" fit on a forklift, unless you're talking fry tanks.

My intention would be to use IBCs exclusively.

Where I live seasonality precludes some very marketable fish species. For example I could probably grow Barramundi and Jade perch in greenhouse for the summer and move them into a climate controlled environment to finish them off. The same goes for trout our summers are a bit too warm to grow trout particularly in a greenhouse but even outside we would struggle with temperature issues. We can keep Silver perch here all yaer round but they become sulky, don't eat and virtually hibernate and cease growing as the temps drop. That isn't good for the bottom line of a fish business. Fish outside of an appropriate temp range feed poorly and are prone to stress and disease.

As for the plumbing, it's not really an issue. As IBCs are uniform in size they are easy to position precisely as you can slide then across the hard-standing and into position without damage and PVC barrel unions will take care of the detach/re-attach issues.

Tanks of fish can be removed from growout and placed on life support staged and ready for processing. You can even tip them to remove fish instead of netting. This is not a small issue when you start processing commercial quantities of fish, This is commercial not backyard you need appropriate solutions to manage the quantities of product and reduce manual handling.