Aquaponic Gardening

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So here is my sketchup for a system I've designed.  Background: There is a new vertical greenhouse that will be built in downtown Jackson, WY.  It will be on a 4500 sq ft plot, and go up 3 stories.  (verticalharvest.org)  The public will be allowed access to the first floor, and the top 2 floors are going to be used to grow hydroponic vegetables.  

My idea is to get an aquaponic system in the greenhouse for public education and to build interest in aquaponics.  

I would propose that they set aside roughly a 10' by 10' space for this project.  My design has a few unique factors, first is the L shaped fish tank in the foreground, which will house native trout, and be set up to mimic the trout's natural habitat.  Also, I chose to separate the grow beds into 3 different types of bed (flood and drain on the left, constant flood in the middle and a float bed on the right).  

The initial issue I foresee is how to keep this water cold enough for the fish - are there water chillers out there that could cool the roughly 300 gallon fish tank?  Also, would the vegetable plants dislike 45 or colder water temps?  I know these trout need highly oxegenated water, but I haven't built any kind of aeration into this system yet.  

I have no idea if they will even look at this idea, but I think it will be worth at least nailing down a design and then attempting to present it to the people who are building this greenhouse.  I designed this fairly quickly today, so any comments on this design would be welcome!  

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Many trout can tolerate warmer temperatures in so far as there is enough oxygen available. You'd be better off running water in the mid sixties for your plants and bacteria and avoid the expense of the chiller. Highly oxygenate the water, provide decent flow and find a species like the Rainbow Trout which can do fine in the mid sixties. Your system will be far better off at 65 than trying to run in the mid forties as your nitrifying bacteria will be non-functioning and your nitrites will go through the roof. 

I forgot to say that I like the design though... not sure you need to elevate the return pipe so much, but the layout is cool. 



JD Sawyer said:

Many trout can tolerate warmer temperatures in so far as there is enough oxygen available. You'd be better off running water in the mid sixties for your plants and bacteria and avoid the expense of the chiller. Highly oxygenate the water, provide decent flow and find a species like the Rainbow Trout which can do fine in the mid sixties. Your system will be far better off at 65 than trying to run in the mid forties as your nitrifying bacteria will be non-functioning and your nitrites will go through the roof. 

JD, I'm guessing the pipe is going up and over because that is the walkway into the system.

Now it seems to me a horrible waste of space to have the fish tank elevated on a stand and nothing under the stand like that.  Seems you might do far better having a deeper tank.  Why not let it go all the way to the floor?  Otherwise it looks like an incredibly shallow tank for trout.

Now it also seems like a rather small amount of grow bed for the amount of fish tank, the stocking density on the fish will have to be kept way low to keep from overpowering that small amount of grow bed.  I would recommend making the footprint of the fish tank a bit smaller but the tank could be deeper so will probably still have more water and then you can use some of that space to add more grow beds.  For 300 gallons of fish tank, I would highly recommend at least 300 gallons of media bed to provide filtration (and at the lower temps, you need more grow bed to keep up with carnivorous fish like trout.)

Thanks for the input JD. And TCLynx is right about the pipe being elevated over the entrance.  The greenhouse is planning on employing people with disabilities, and my thought was to keep the floor level as clean as possible to allow access for all workers.  One other option is to run the pipe all the way around the underside of the support tables.  Which would eliminate the unsightly pipes above and also lower the amount of lift needed to get the water back to the fish tank. 

I'll also be using native cutthroat trout, as opposed to rainbows which are not native.  Was also considering running some pipes outside to cool the water in winter, but the more i thought about it, the less attractive the idea became when I envisioned bursting pipes and the need to constantly monitor the temp.  If this project moves forward at all, I will try to talk to the local hatchery employees to get some ideas.

TC - I definitely considered making the fish tank go all the way to the floor, however, since this is a sort of "educational" setup, I'd like the public to be able to see the fish swimming, as opposed to people just staring into a deep tank where they may not even be able to see the fish.  But the option is definitely there to deepen and shorten the tank and add one more grow bed or even a vertical tower (keeping with the vertical harvest greenhouse that it will be housed in). 

I did size these grow beds according to the rules of thumb and they seemed to came out in balance, but maybe i missed something.

Further nitrification will come from the local rocks that I will be placing in the fish tank - there is a creek near here that has the highest rate of nitrifying bacteria in the country.  Hopefully that extra media in the fish tank will allow for a nice amount of fish stock in the tank. 

I was planning on proposing to make the fish tank and grow beds myself, by the fiberglass on wood method.  Has anyone built a custom tank in this manner?

Thanks for the replies!

JK


JD Sawyer said:

I forgot to say that I like the design though... not sure you need to elevate the return pipe so much, but the layout is cool. 



JD Sawyer said:

Many trout can tolerate warmer temperatures in so far as there is enough oxygen available. You'd be better off running water in the mid sixties for your plants and bacteria and avoid the expense of the chiller. Highly oxygenate the water, provide decent flow and find a species like the Rainbow Trout which can do fine in the mid sixties. Your system will be far better off at 65 than trying to run in the mid forties as your nitrifying bacteria will be non-functioning and your nitrites will go through the roof. 

Rocks in the fish tanks are not really recommended, when you do that you wind up needing to vacuume out the waste that tends to collect in the rocks rather than letting it just flow through to the grow beds.

I have deep tanks and as long as you keep the water quality good, the fish are visible down in deep water.  And remember that trout Jump!  You need a way to keep them in the tank rather than flopping on the floor.

Well hard to tell from the picture I guess but looking at the media beds, it looks like you have perhaps 18 cubic feet of media and then 9 square feet of raft.  So are you planning on only about 20 fish MAX in the system growing out to perhaps 1 lb each?  I say 20 because I'm figuring 1 trout per cubic foot of grow bed and then one fish per 3 feet of raft so that would make 21 the max number but with trout eating high protein feed you can likely get away with even less fish.

First, great idea. I had similar thoughts when I heard of Vertical Harvest. Wyomingites love trout.

I hope the new building has a ground source heat exchange. This would provide you with all of the water temp conditioning you would need, regardless of the season. I've not heard anyone talk about this, but with heat exchange technologies being what they are, we can take energy out of the water coming out of the grow bed and put it into the water going into the grow bed, bypassing the fish tank. (The heat energy bypasses the fish tank, not the water) In this way, we could give the trout (or other cold water fish) water at the best temp for them as well as water at the best temp for the plants, without  a lot of expense.

I have little expertise on showcasing the different methods of growing. My inclination would be to keep it simple, and demonstrate the viability and value. The mental leap to different methods is easy, no?

I like the idea of creating stream-like flow, both for the fish and spectators. Pipes under or alongside the beds/tanks to minimize lift is a good idea. Tanks all the way to the floor is a good idea as well.

Acrylic bowls work as viewers, eliminating the visual interference at the surface. Soon someone will put an underwater cam in their tank so we can all watch their fish.

Hi Brant, re: the heat exchange idea, it all depends on what you would call "a lot of expense" heat recovery exchangers have come a long way but there is no perfect heat exchange and if you are trying to do it beyond ambient variations, you need compressors which certainly adds to the expense.  I know there have been some operations advertizing package systems that do this but so far I have never seen any pictures of an actual real aquaponics set up where they are chilling the water down for the trout or salmon and then warming it up for the plants and then chilling it back down for the fish again.

Now if some one knows of an actual aquaponics system that is doing that, we would love to hear about it, but so far it seems to still be on the bleeding edge of technology and aquaponics is already costly enough.

Hi TCLynx,

I agree with you if "ambient" means only the energy in the room and the energy in the water in the AP system. If it includes nearby energy sinks and sources, like an existing ground source loop (my optimistic assumption in the above case)  and a roof,  no compressed refrigerant is needed.  I'll stop here to avoid hijacking this thread. I'd be happy and interested to discuss this further, if it seems productive. I'm a complete neophyte on all things AP, but not on energy transfer. (I didn't mention evaporative coolers because I can't argue that it isn't a decompression technology)

brant

TCLynx said:

Hi Brant, re: the heat exchange idea, it all depends on what you would call "a lot of expense" heat recovery exchangers have come a long way but there is no perfect heat exchange and if you are trying to do it beyond ambient variations, you need compressors which certainly adds to the expense.  I know there have been some operations advertizing package systems that do this but so far I have never seen any pictures of an actual real aquaponics set up where they are chilling the water down for the trout or salmon and then warming it up for the plants and then chilling it back down for the fish again.

Now if some one knows of an actual aquaponics system that is doing that, we would love to hear about it, but so far it seems to still be on the bleeding edge of technology and aquaponics is already costly enough.

Brant, might be worth starting a discussion thread about the heat exchange/energy transfer methods you are talking about since I am indeed sure there are people interested.  (of course in my location it wouldn't make a difference, compression/decompression technology would be mandatory to grow trout since our ground temperatures only get down to about 72 F from a deep well here, which works for keeping tilapia warm in winter but not to chill water for trout in summer.)  I did a bit of research on geo-exchange heat pumps when working on the design for my hopefully future house.

Brant and TCLynx - thanks for your replies.  after thinking about this idea this weekend, I came to the conclusion that it wouldn't make sense to showcase native trout in an aquaponics system.  If the idea is to show the public how simple, easy and fun it is to create an aquaponics system, and be able to grow veggies year round (with a nice fish protein kicker), it would make more sense to include those species of fish that would be most used around here.  My guess would be the old tried and true tilapia.  This will eliminate the need for cooling the water, and it will also allow my design to look more like what it will look like in someones greenhouse (or basement, in my case).  

As a result of this thought process, I'll probably be changing the design to include a deeper tank and increase the grow bed sizes.  Also, I think Brant's idea to only show one type of growing methods also makes sense.  I'll probably be reworking the design, so any ideas on how to keep it contained in a 10 x 10 foot space are welcome!

JK

Hi James

Don't be so quick to blow off trout, anyone can grow tilapia but trout are well worth the trouble.     If you do a search online you will find that many people have trout aquariums in their homes. The only trick is water flow and a water chiller set to 60F.  Remember, you are in naturally cold country up there in WY; not steamy Florida where tilapia thrive.

I personally think your plans are too modest.  I'd plan to buy fingerlings from the local hatchery and grow them out for sale to the visitors.    Think about making a stream with a splashy riffle for free O2 enrichment that runs below long raft beds stationed above the stream. The water is pumped from a sump into the raft and media beds. The water exits the beds and cascades back down through the rocky riffle to a fish tank; a classic pool and drop trout stream.  Then exits the FT into a gravel worm bed filter/sump set up.  If water temp becomes an issue, a small window unit a/c will provide chilled water with a little inspired retrofitting for about a $100*.  My only pump is a 3/4 hp pump rated at 2880 g/h it covers the raft beds and an ornamental waterfall the returns to the FP via a splashy stream (10'x 2' with 2.5' vertical drop) for O2 enrichment, handles the O2 needs of 40 full size fish in 500 gals. and looks great in the backyard next to the patio.  ;-)

Follow your dreams man!

* remove the cover and indoor fan motor, create a 5 sided cube for a water enclosure around the indoor coil, create a flow through inlet and outlet water fitting for the enclosure.  Tap the falling H2O at the top of the riffle and return the chilled water before the FT.  Be sure to add local rocks with local aquatic life such as mayfly nymphs to the riffle for bacteria and an additional free food sources

Jim - thanks for the ideas!  I'd love to see pics of your set up and maybe start adding these ideas into a design.  

Sure don't want to give up on the trout idea, especially if it will further inspire folks to start looking into AP for themselves!

JK

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