Aquaponic Gardening

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I set out probably a year ago to see if I could raise tilapia in a series of 50-gallon food grade barrels.  I have been tinkering with the setup and now I believe I have reached a point where I can start to consider adding some complexity to my system and incorporating some aquaponics. I am joining this community to pick up some tips and discuss problems as I begin this process.

My aquaculture setup as it is consists of three barrels arranged in steps.  Water flows in series through two barrels which are used for habitat (with space for adding another) and then to a biofilter barrel.

The #1 tank contains the adults.  A 1 1/2 inch outlet leads to the #2 tank, where juveniles are swept due to water currents. The #2 outlet is protected by a fine screen and leads to the top of the biofilter: first a 24" diam x 4 inches thick polypropylene matt filter, then two rolls of polypropylene/ calcium carbonate ribbon, with a 24" aerator disk through the water flows. 

In the bottom of the barrel are the pumps:

One water circulation pump cycles water from the bottom to the top for an extra pass through an aerator shower and back to the top of the biofilter.

Three redundant waterfall pumps lift the filtered water about three feet to a 1-1/2" fresh water supply pipe, which returns water by gravity to tank #1 through a manual valve. This water line also has taps to access water for watering plants, and for another 45 gallon glass fish tank intended as a breeding tank.

One pump lifts the water 12 feet to a solar collector for heating; this is controlled by a switch which enables the solar heater when the collector has reached a high enough temperature, and a thermostat to shut off the pump when the habitat reaches the desired high temp of 95 degrees. In addition there is an electric heater which ensures a water temperature minimum of 70 degrees.

Another collector pipe collects the solar heated water and returns it to the aerator shower and top of the filter. There are provisions to accept other return water inputs, such as water from a remote breeding tank, not fully integrated. 

In addition to the barrels previously mentioned, there is a make-up water barrel, which collects rainwater and/or dechlorinated tap water, and supplies water to top off the system when water is removed.  Another separate barrel is used for conditioning tap water and collecting excess rainwater runoff.

I routinely draw off water from the system to water my container garden.  This is a series of soil-based planters, and there is no collection and return of water that passes through them.  I also have a worm compost bin.  The entire setup is contained in my patio, which is roofed and enclosed with transparent polycarbonate to extend the growing season, so all lighting is natural and subject to seasonal variations, such as there are in Southern California.  This is OK with me, I think I can live with these limitations.

This is my system as it stands.  I am now considering appropriate plantings in hydroponic beds for veggies both summer and winter.  I want tomatoes, squash, snow peas, green beans, root vegetables, sweet potatoes, herbs, and greens, and I can choose the ones that lend themselves to the medium best, using conventional methods for the rest. Now to see what I can learn.

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Comment by Hal Hurst on November 5, 2012 at 12:50pm

I see I did not answer your question below concerning pump regulation and conrol, so here goes:

The system is enabled when the space next to the coils warms above 90F and disabled below 80F to prevent cooling the water when the sun isn't strong enough. This is accomplished by this cheap snap disk attic cooling fan controller. There is another heating thermostat with remote bulb which also must be enabled for the pump to work (wired in series) which serves to shut the pump down when the water is hot enough- Set to 90F. I would verify the action of this thermostat experimentally to prevent overheating the fish.  My strategy is to warm the water to the maximum during the day, and hope the insulation in my tanks limits the heat loss enough to prevent the temp dipping below 75 on nights following cloudy days.  That's when my night heater will kick in as required. 

Comment by Bart on November 4, 2012 at 6:55pm

Cool thx Hal, I will have to take a look at it later in the week - the wife is starting to refer to herself as an aquaponic widow lol.

Have a good one.

 

Comment by Hal Hurst on November 4, 2012 at 5:36pm

Bart, for your consideration this winter I submit my journal on setting up my first hydroponics bed on myFolia.

Comment by Bart on November 4, 2012 at 5:19pm

thanks Hal, I appreciate the feedback. I'm going to put my solar plans on hold for now, it's getting too cold for me to enjoy the outside work right now (going down to about 25F tonight) For now all my critters are in the basement where it's nice and warm, i just picked up another aquarium heater today for the second tank with tilapia, what a difference 10 degrees makes. Once the tank was up to 80F for 7 hours or so there was a noticable difference in the activity and feeding of the fish. clearly anything below 72F and these tiliapia shut down. Learning as I go 

I might look at doing the solar coil in the spring, so will likely have some questions at that point - at least i have something to work with over the winterr to scheme and plan with - the wife loves it when that happens lol.

Cheers.

Comment by Hal Hurst on November 1, 2012 at 8:42am

My pump is sized to raise the water to the highest point- about 16 feet.  Theoretically you can get a good enough seal once the piping is  filled to ease the load on the pump, but Murphy's law usually ensures that there is some air getting in there overnight.  So the pump must be sized to do the job on its own, and the flow rate will increase once the downhill side starts to have its effect. To help this process, you may want to consider piping the shorter path uphill to the peak, and put the coils on the downhill side.  I split the return into two parallel sets of coils to minimize the resistance of all that length.

The pump is a common waterfall pump available in hardware stores.  As I mentioned above check that the specs show that the pump can pump water to a few feet higher than your highest point, to get the system primed.  As far as the flow rate is concerned, it is far faster than I absolutely require- the water is only a degree or so higher on return- so that means that I could probably triple the length of the coils and be fine. But I have enough length for my needs here.  I could consider reducing the size of the piping, but the surface area is the collector, the tubing is a common size, and twice as much smaller tubing would cost me more, so I will leave things alone. I don't mind piping a lot of water because it sources in the downflow side of the biofilter and returns to the intake, where it increases the efficiency of the filter with an extra pass.

Note that the water level in your system will be affected when you turn your system on and off, as the water drains back to your source.  200 feet of 1/2 inch coil = 30 liters.

Comment by Bart on November 1, 2012 at 7:27am

Sorry to hear about your fish. I'm at the point where I have backup concerns as well, we caught just a touch of the Sandy storm, I was ok but people not far from here were out of power.

I've been looking into UPS's for computers, there's one out there at The Source (same as Radio Shack in the US) for $50 looks like it should run my 5 watt air pump for a few hour - although I'm not sure how to calculate this so I think I"m going to just have to try a small one for now and see what it can do.

Vacuum tubes are definitely costly, but the pricing is coming down fast as the adoption rate climbs. I've been thinking of doing something for a while now - i'm into that a little, I have a 10KW grid tie PV system on my shop.

?? how do you circulate the water - is there a pump that turns on and off based on the water temp or the temp in the solar collection space between the rafters?

You are pumping water pretty high to get it up over your head - or is it a case that by piping the water back down there is an offset in the head presure by the suction of the water coming back down? I've never read anything on that but it might make some sense I guess.

 

 

Comment by Hal Hurst on October 31, 2012 at 10:29pm

Oh, Vacuum tubes = heat pipes, plus a Dewar flask to contain them, without the silvering.    As a former refrigeration repairman I'm acquainted with how they work. Pretty high-tech for my backyard, but my needs are modest.  The pipes depend on the evaporation and condensation of some liquid with the right boiling point sealed inside, and gravity to return the liquid to the bottom to be heated again. I guess you would tilt them toward the South on an angle perpendicular to the angle of the sun at high noon on the winter solstice, if you plan to use them in the winter.  Great demonstration. But I bet they cost a fortune, compared with the energy they will save.  Maybe not, with fuel prices constantly rising.

Comment by Hal Hurst on October 31, 2012 at 10:09pm

My tilapia are down to two adults and a half-dozen fingerlings, due to a power failure and loss of circulation and aeration for about 10 hours.  The larger fish seemed more susceptible to to this- they were at the surface drinking air when I came home from work, and over the next four days about 5 died off.  My system is vulnerable to power failures- not enough surface area for passive oxygen exchange, no backup system to power an aerator.  No solution comes to mind other than putting the fish in a wide shallow pond, which is a non-starter for my space.

My solar piping is just below the polycarbonate roofing, where hot air would collect, in the boxed area between the joists. Maybe there is an advantage to this- I thought it couldn't hurt. in any case it's the warm air that actuates the fan thermostat that turns on the solar collector, and the sensor is jammed right up there at the top of the enclosed space as well.


I will check your link later, but on the face of it vacuum tube anything sounds pricey.  On the other hand, my roof never sees snow, and so there will be no need to get rid it to allow sun on the coils.  I hear it snows in Ontario from time to time. You will have to figure out how to handle that.  Maybe just make it steeper?

If you get any ideas on how to make my system power failure safe, please pass them along.

Comment by Bart on October 31, 2012 at 8:52pm

Hal, I missed they reply you put up to my questions until now - it has been nuts around here so not so good at following up on things. Your barrel system is similar to mine, three barrels in series cascading one to the next, only after my third barrel i have the bottom of an IBC with about a foot of crushed clay brick for media as my filter, seems to be working so far  

Thanks for the info on the solar heating. Getting a 10 degree increase in three hours of solid light sounds pretty good or an investment of 200' of poly 1/2". One question on this - is the poly under the polycarbonate or is it outside?

Example of vaccuum tube solar heating:

http://www.youtube.com/watch?v=bCbg9XCoR_8&feature=related

 

How are your fish doing? I just picked up my first Tilapia - i'm in southern Ontario - just a little cooler then CA lol.

Comment by Hal Hurst on September 10, 2012 at 5:09pm

I went the expensive with my two spools of springflow medium, after using polypropylene tulle (that gauzy fabric used for tutus and decorating wedding tables).  Tulle's 1/8" holes were not enough  to let air bubble through, when I was trying use a counterflow aeration in my filter.  I would say anything would have to have at least 1/4" holes in order not to capture air bubbles.  I was not in the mindset to so any more experimenting at the time. As it happens it was critical for me to consider both the total surface area of the of medium and the rate the water flows through it (gph).

I second wer winn's thought that gravel or some kind of rock would be very hard on the back, shoveling it out of a 50 gallon drum.  My stuff is light enough to gather up and stuff into a mesh laundry bag when I have to clean my filter, and weighs 5-10 pounds when drained. So you would be wise to consider how you would handle something so heavy.  My prefilter helps catch a lot of the sediment before it gets into the lower parts of the filter, and allows me to limit the need to totally dismantle the filter for cleaning.

The ability of nitrobacter to cling to the surface of whatever you use might be important to you: so as far as rock goes, porous lava might be better than smooth round stones- more surface area.  The more porous or fibrous the better. Maybe you could find cut off polypro rope ends or even rejected plastic parts. The other thing is whether anything will leach out of it into the water. So be careful about some plastics, and also carbonate (limestone) bearing gravel, for different reasons..

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