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PostPosted: Jul 6th, '15, 09:21 
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Seriously, this cant be healthy.
Seriously, this cant be healthy.
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Damian wrote:
Tilapia is the fish being used have a 6 month cycle so if harvest is once a month the system needs will fluctuate by 1/6 (or 16%) per month. The needs will also spike at feeding time which is 3-4 times a day, if you feed all the fish at once it requires (from memory) an increase in about 20% of the flow rate to compensate for about 1 hr after feeding, therefore you only need that extra 20% for 4 hours of a 24 hour day. Then there is seasonal temperature changes affecting the needs also i think that by the time this system approaches its 6 fish harvest you would have only used the equivalent energy for 5 traditional fish crops.


Yes which is why commercial systems use variable speed pumps. Controlling flow relative to feeding regime, temperature and a bunch of other factors is a good idea but its not a basic system. For it to be worth doing you need to be producing a LOT of fish.

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PostPosted: Jul 6th, '15, 09:43 
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Seriously, this cant be healthy.
Seriously, this cant be healthy.
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On the other hand varying the rate of flow relative to bio-mass is simple. As part of you management you should have an idea of your total biomass and as it grows you just increase the flow.

Its another example of how scale helps.

Just say you have a system that goes through a regular bio-mass cycle. You have a basic way of increasing the efficiency of your system by ramping the flow up as bio mass increases.

Let's say you have a good backup system that HAS to be sized to deal with the power requirements of the system when the fish are a day or two from being harvested. For much of the year a lot of that backup capacity is not needed.

To increase your scale you add in another identical system but you don't need to increase the capacity of your back up system by much if you run the second system out of sink with the first system. The second system is a bit cheaper to build and you begin to spread out your production so that you can supply your market more often and more regularly.

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PostPosted: Jul 6th, '15, 11:05 
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i should be running at about 150kg/every friday.....

what is a good pump that can handle 400gpm @5 foot head?


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PostPosted: Jul 6th, '15, 13:01 
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Stuart Chignell wrote:
Damian wrote:
Tilapia is the fish being used have a 6 month cycle so if harvest is once a month the system needs will fluctuate by 1/6 (or 16%) per month. The needs will also spike at feeding time which is 3-4 times a day, if you feed all the fish at once it requires (from memory) an increase in about 20% of the flow rate to compensate for about 1 hr after feeding, therefore you only need that extra 20% for 4 hours of a 24 hour day. Then there is seasonal temperature changes affecting the needs also i think that by the time this system approaches its 6 fish harvest you would have only used the equivalent energy for 5 traditional fish crops.


Yes which is why commercial systems use variable speed pumps. Controlling flow relative to feeding regime, temperature and a bunch of other factors is a good idea but its not a basic system. For it to be worth doing you need to be producing a LOT of fish.

Many years (15 or so) ago I used to work in a chemical process environment. I had great success with a (If memory serves) Gould 1hp nema C face mount stainless steel pump on a cheap VFD (Maybe $250, long time ago) . They were CHEAP (~650USD at the time) with great flow specs, and would run down to below , i think, about 25% flow reliably, stop/start/etc, and didn’t complain at 120+Hz (almost 2X design speed, minus efficiency losses.). I did spin them faster, but only in tests or commissioning. I wasn't comfortable with it for SOP, though nowadays the manufacturer would surely spec a max rotation, at the time vary few suppliers were familiar with VFD on such a small mover.
Stuart, I expect that this is not news to you, but for Damian and others like him, do not hesitate to start looking outside of the BYAP range of pumps, and into industrial (chemical process) equipment at or even before the 1HP mark.

Oh, and my experience with automation, I can provide three insights:
If you double the most you can imagine it might cost, you will be close. I recall that many devices required specific interconnect wire, at a non-negligible added cost.
When it was part of my FOE, the configuration of the control system (PLC) required programming level knowledge, and most systems had their own language idiosyncrasies to learn. At times, the GUI setup was bad enough to make me think that 1980s/90s ladder logic had been easier.
The finest process control system is a poor replacement for a human oversight. The most I would ever expect of the computer is to keep everything ticking along WHEN ALL IS WELL. The failsafe will (or at least should, IMO) always be to notify an operator of the anomaly. The operators first duty is usually to verify that there is an anomalous condition, as opposed to an anomalous reading. To do that, the operator will need to be readily available to the site at all times.

Please do not construe this to be an indictment of the controls, I would/will use them even at a BYAP scale. What I would not do at any scale is rely solely upon them.

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PostPosted: Jul 6th, '15, 13:16 
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Gingerbread Man wrote:
Stuart, I expect that this is not news to you, but for Damian and others like him, do not hesitate to start looking outside of the BYAP range of pumps, and into industrial (chemical process) equipment at or even before the 1HP mark.

There are a few google searches along that line that will keep me busy for a while. I hadn't thought of looking a chemical process equipment for pumps. Especially such small ones.

Gingerbread Man wrote:
[lots of good stuff cut]
Please do not construe this to be an indictment of the controls, I would/will use them even at a BYAP scale. What I would not do at any scale is rely solely upon them.


Yeah nothing beats 24hrs human supervison but again we come back to scale. To afford round the clock supervision requires scale and the dollars that come with it.

Its also good to seperate out in your mind at least two separate jobs. Control system and Monitoring and Alarm system.

Control system helps you run the operation more cheaply and more efficiently.

Monitoring and alarm system helps you to manage disasters minimising the amount of damage and the level of impact of any disaster.

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PostPosted: Jul 6th, '15, 14:48 
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I am really digging the feedback thanks............will look more into those pumps for sure, i am on 50hz would that affect a VFD? can that type of pump handle the solids in the water?....... for now i want get the basic methodology of control systems and monitoring/feedback systems and a general idea of the cost/savings. If this could limit human involvement to the bare essential it would be nice....... someone will be always on site regardless.

You made a good point about controlling flow relative to expected biomass vs controlling flow relative to feeding regimens temperature and other factors, which translates to Actual biomass. A 20 year run would be nice, over that time savings COULD be tremendous if controlling for actual biomass rather than expected biomass. In my original design (influenced by smaller pumps) the fish are batched by month and the plants by week each batch having their own monitoring and control mechanisms you're saying that to justify this i have to be producing huge amounts of fish well i want factor in time, at least to ROI and compare the two as best as i can.

It seams like a big problem area is physically linking the monitoring equipment to the pump(s)


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PostPosted: Jul 6th, '15, 21:45 
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My research last night led me to Heating Ventilation and Air Conditioning (HVAC) system design and in particular Variable air volume(VAV) VS. constant air volume(CAV) which i believe is the same or very similar argument we are looking at here. we look into this some more to see if i can find anything usefull.


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PostPosted: Jul 8th, '15, 03:41 
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The only benefit i can see with Actual Biomass Derived Control (ABDC) is predicated on the notion that your fish are compartmentalised by growth rate, therefore this would only be feasible if the differences in energy requirements at the varying growth rates are less than applying the requirements of the most demanding growth rate to all other growth rates. Estimating this would not be simple but is possible as there is work done on the varying growth rate needs of tilapia.

More about how the physical ABDC system could look like............. I believe calculations would have to be based more on retention time than turnover rate as the main flow would be going at minimum rate to maintain constant chemical water quality parameters and each of the loops connected would be controlled by retention time relative to the main flow. the secondary pumps would be very small (read cheap) in comparison as they would only be adding to the already present flow.

Kinda like having one large pressurized sump with a separate pump for each component in parallel.

Edited to add: Assuming the energy requirements of the main flow in a abdc system are lower because you could run lower than normal DO levels.


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PostPosted: Jul 8th, '15, 07:15 
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Damian you are trying to talk about and work on designs that are seriously complicated without the foundation of knowledge to build your ponderings upon.

The guys at no less an institution than Cornell are working on these problems right now. You on the other hand don't have some of the basic concepts under your belt.

Damian wrote:
I believe calculations would have to be based more on retention time than turnover rate


Maybe its a language barrier thing but I don't see any difference between retention time and turn over rate.

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PostPosted: Jul 8th, '15, 16:23 
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Stuart i cant tell you how much times over the years your signature has saved me, before any building i ask my self "what does the math say" and in answering that i usually can weed out the really bad ideas.

We can learn as we go along, if Cornell is on the case then we must be on the right track with this. We as so shouldn't let them have all the fun. Theoretical math in AP is actually fun for me, very basic though.

I kinda lost my train of thought about the retention time / (total tank) turn over. I was trying to highlight the fact that a system like time may be better with small tanks in the range of 100 kg of fish therefore useing RT over TTT may be a better choice.

I am using UVI numbers to calculate the exact feed regime of the fish. How feed amount per m3 translates to kw hours @ X% efficiency i am completely lost right now though.


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PostPosted: Jul 12th, '15, 19:33 
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putting this image out there for any ideas/feedback

fish are a 6 month crop and the plants are a 4 week crop

Also looking at cheap yet reliable ways to get data from the system to use to control the pumps i am thinking Video for the fish and "rate of ph change" for everything else.

meaning at the different stages in the nitrogen cycle ph will be doing different things. kinda like a ph "stratification" within the different loops of the system. just speed up or lower the flow through a particular loop to adjust.

BTW The 20 foot RFF is to help stabilize temperature.


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PostPosted: Jul 12th, '15, 21:10 
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http://www.akvagroup.com/products/cage- ... -estimator

something like this for video monitoring


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PostPosted: Aug 19th, '15, 04:36 
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Gingerbread Man wrote:
Many years (15 or so) ago I used to work in a chemical process environment. I had great success with a (If memory serves) Gould 1hp nema C face mount stainless steel pump on a cheap VFD (Maybe $250, long time ago) . They were CHEAP (~650USD at the time) with great flow specs, and would run down to below , i think, about 25% flow reliably, stop/start/etc, and didn’t complain at 120+Hz (almost 2X design speed, minus efficiency losses.). I did spin them faster, but only in tests or commissioning. I wasn't comfortable with it for SOP, though nowadays the manufacturer would surely spec a max rotation, at the time vary few suppliers were familiar with VFD on such a small mover.
Stuart, I expect that this is not news to you, but for Damian and others like him, do not hesitate to start looking outside of the BYAP range of pumps, and into industrial (chemical process) equipment at or even before the 1HP mark.

Oh, and my experience with automation, I can provide three insights:
If you double the most you can imagine it might cost, you will be close. I recall that many devices required specific interconnect wire, at a non-negligible added cost.
When it was part of my FOE, the configuration of the control system (PLC) required programming level knowledge, and most systems had their own language idiosyncrasies to learn. At times, the GUI setup was bad enough to make me think that 1980s/90s ladder logic had been easier.
The finest process control system is a poor replacement for a human oversight. The most I would ever expect of the computer is to keep everything ticking along WHEN ALL IS WELL. The failsafe will (or at least should, IMO) always be to notify an operator of the anomaly. The operators first duty is usually to verify that there is an anomalous condition, as opposed to an anomalous reading. To do that, the operator will need to be readily available to the site at all times.

Please do not construe this to be an indictment of the controls, I would/will use them even at a BYAP scale. What I would not do at any scale is rely solely upon them.


I have replaced the first idea of multiple pumps with just two, one for fish one for plants, where I would of used the other pumps I will use ball valves and flow meters. All feed and drains are 2in to 4in.

Not really sure about pump selection I am hoping Stuart and others can help. I need a constant 400 GPM flooded suction head off 6 feet. And the option of remote control or at least programable is also needed.

Been looking at burkley pumps from pent air.

What should I be looking for when I want to buy such a big pump?


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PostPosted: Aug 19th, '15, 04:54 
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Damian wrote:
http://www.akvagroup.com/products/cage-farming-aquaculture/camera-systems/biomass-estimator

something like this for video monitoring

Once again you post something so contradictory.

On the one hand you seem to be doing everything you can to reduce costs and you say your budget is really tight and then you post something like that. Do you realise how expensive that piece of kit is?

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PostPosted: Aug 19th, '15, 05:51 
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I said SOMETHING like that something magiver would build. Was thinking PET bottles with webcams or even a cheap security system.


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