Low Energy Aquaponics - LEAP

[velacreations]

I started a thread over at BYAP to get some input on how we could develop a low energy aquaponics system that could be powered by solar. Here's the link: http://www.backyardaquaponics.com/fo...d52bc327ef5df3

The idea is a system with a max requirement of 10 watts. The solar component for a 10 watt system can be had for under $400 USD. Of course, if we can get the power down even further, that's fine, too.

To meet this goal, the going idea is a constant flood, constant height (zero/low head) recirculating system. We're looking to turn over the FT volume every hour at least, and stock at appropriate rates (maybe up to 25kg/m3).

The response has been awesome, and currently, the talk is about using airlifts or powerheads for circulation. Folks are running tests, and a member has achieved 1200 lph with 5 watts on an airlift, making that do a 1,000L FT (IBC) just fine.

Just to be clear, that's a $300 USD solar system for a 1,000L FT and 1,000 GB in a constant height, constant flood configuration.

So, I want to get as many ideas as possible, so what are the thoughts over here? How would YOU do a 10 watt system, and how can we stretch the limits of the box to make this work?

[GaryD]

Hi Abe,

The idea has merit......although I'd recommend that you incorporate some basic solids removal device into the design.

While I'd make that recommendation anyway, I think that it's particularly important in your case.....since you it would be very difficult to clean that grow bed without impacting the fish......and (contrary to what you might read elsewhere) you are going to have to clean it.

Dr Wilson Lennard recommends that grow beds should be cleaned at 3 - 6 monthly intervals.

The pipework needs to be set up in such a way that you achieve the maximum water changeover (no dead spots)......and, although you are attempting to minimise power consumption, you will still need a minimum flow rate......just to keep the solids moving out of the fish tank.

Have you contemplated a mini-wetlands approach.....where you have a couple of extra chambers, each of which deals with a particular aspect of water quality management?

Gary

[ande]

Hi velacreation
I think this thesis
A THEORETICAL AND EXPERIMENTAL STUDY OF AIRLIFT PUMPING? AND AERATION WITH REFERENCE TO AQUACULTURAL APPLICATIONS
Presented to the Faculty of the Graduate School of Cornell University
In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Douglas Joseph Reinemann August 1987

edit to insert link http://www.uwex.edu/uwmril/pdf/Rural...D%20Thesis.pdf

Allredy crunches alot of the numbers on airlift/RAS I'w read the thread(s) inkl. the criss cross to BWII snowt with amusement and intrest
I lean towards favouring airlift as compared to axialpump (no or low lift / high volum water displacement) new akronym needed ? hehe
Would that be "NOLL" / "HVWD" or "NOLLHVWD"
there is some recent threads on here

I think this subject is also highly relevant in a commercial training course, dissecstion off........... Powerconsumption (energi volume) and the price$ is a primary key factor towards to sucsess/failior and a potential limiting factor just like water in a RAS

cheers

[velacreations]

the exact layout of the system hasn't been figured out, yet, but I am leaning towards what user Jimbo has going with his IBCs: http://www.backyardaquaponics.com/fo...b5bdf7f69cd50c

The minimum flow rate is turning over the FT in an hour, so for a 1000L IBC system, that would be 17lpm or better.

[velacreations]

Gary, what sort of mechanical filtration would you suggest? And how do people clean their growbeds? I haven't seen anyone mention that.

A wetland approach is interesting, how would you set that up? And diagrams?

[JohnMc]

For solids removal I don't think it would be necessary to run constantly would it? For example use the low wattage side as described. Then use a higher power system in cycles to remove solids but still keep the total power requirement low.

[Pseudoreality]

I would take a step back to see what your goals or rules are for this design first. Then I would ask if you need a media bed. The media bed is used in the BYAP set-up as an all-in-one solids filter, bio-filter, and growing area. Problem is it's not very efficient at any one of those specific things. That's fine for a hobby system, but if you are trying to design a system to minimize your energy use you may need to take a step back and look at the bigger picture. Media provides friction and you'll see a lot of head loss that you might not need from a pure bio-filtration point of view. I would look into a sedimentation step (swirl or tube settler) and efficient bio-filter (eg. K1). Then I would consider a NFT or raft system growing area that exposes a lot of water to the area (i.e. shallow) for air exchange, but shade it to prevent algae growth. After that I would carefully calculate the O2 balance in your system to see if you really need to change over the water once per hour.

Sounds like a fun project. I like design challenges and I love looking out side the box.

[velacreations]

maybe even do solids with a gravity system, so they settle out and the drain them from a clarifier.

[velacreations]

I would take a step back to see what your goals or rules are for this design first. Then I would ask if you need a media bed. The media bed is used in the BYAP set-up as an all-in-one solids filter, bio-filter, and growing area. Problem is it's not very efficient at any one of those specific things. That's fine for a hobby system, but if you are trying to design a system to minimize your energy use you may need to take a step back and look at the bigger picture. Media provides friction and you'll see a lot of head loss that you might not need from a pure bio-filtration point of view. I would look into a sedimentation step (swirl or tube settler) and efficient bio-filter (eg. K1). Then I would consider a NFT or raft system growing area that exposes a lot of water to the area (i.e. shallow) for air exchange, but shade it to prevent algae growth. After that I would carefully calculate the O2 balance in your system to see if you really need to change over the water once per hour.

Yeah, that is good advice. The main goal is to produce fish+veggies at below 10 watts.

I am not an expert on any of this, so I can't comment much on media vs DWC/NFT, but one thought is that with media, you greatly reduce the amount of water required for the same square footage. Then there's issues with anchoring large plants, and DWC systems in particular, require higher aeration rates than constantly flooded media beds. But again, I don't know enough to really be able to compare them.

It does seem like a lot of people have great success with the all-in-one media bed. But, a solids filter is pretty easy to put in there.

As far as media adding drag to the flow, how can we calculate this? The consensus has been that yes, it adds drag, but in reality, not enough to create an issue. I don't know, cause I don't have a media bed here to verify.

Would you be able to put together a simple diagram to illustrate your suggestion? I think diagrams help a lot of us beginners, and it may illustrate some concepts and ideas we haven't reached, yet.

[velacreations]

one thing I have thought about a lot is pipe losses traveling to the GBs.

Now, if we could make a small channel, like a DWC, but inside a media growbed, it would reduce those losses a lot (if we made it big enough). Maybe we could make it in a way to function as a solids filter, too.

So, basically, the pipe from the FT dumps into an open channel that has GB media on one side, the GB wall on the other side. This channel runs the length of the GBs, and serves as a delivery to all of the GBs. Does that make sense?

We'd have to put a drain in there, and maybe some settling areas, but it might be a way to combine a few features into one component.