Tilapia by the barrel

Sweet sounding setup Hal, I'm curious what you are using for solar collector - vacuum tubing style? How large it is and what kind of a temp change it can make on your system in say three hours of straight sun light?

More pics is always a good thing :).

@ bartman: don't know what vacuum tubing might be- I'm using 200 feet of 1/2"  black polyethylene tubing arranged as in the picture I hope to post here.  My transparent roof is held up by five 16 foot 2x8s.  span is approx east and west, so one broad edge is facing the south.  On each southern edge, then, I have placed four passes of this tubing, and each joist is about a foot lower than the one above it, so once the water is lifted to the highest joist, the whole thing drains by gravity back into my biofilter.

Pictures: Upper left: the test fitting showing plan A water flow. Upper right : black tubing on a black painted redwood 2x6 surface, Lower left: tubing partially reinstalled with new flow pattern. Lower right: the final fitting to switch from single to 2 parallel flow paths (less resistance) You can see the polycarbonate roofing also half installed. Because the irrigation tubing did not have a full complement of the fittings I wanted the junction was a plumber's nightmare, But who's going to see, am I right?

I am not too sure about the efficiency heat exchange taking place- so many variables like ambient temp, cloud cover, etc; but on a sunny day I can raise the temp by 10 degrees by noon, in a system containing 150 gallons. And the collector is usually cycled off hours before sunset.  But note that all my barrels are insulated with 1/2" styrofoam wrap. 

Oh Shucks- I forgot which post I was replying to.  For more pictures see the member systems introduction forum.

Hal,

Really like your system lots of questions.  What pumps do you like? Redundancy with multiple pumps. I like it! What gave you the idea? Air pumps types, volumes. did you make your own bubblers?  What would you do different if you had a fresh slate?  I have room for an IBC, (about 225 gallons).  Would you use one as a first tank and then drums or start with drums in a newbie system. 

Thanks werwinn

I am getting my supplies from Home depot, with used food-grade  barrels from the surplus store. The pumps are common waterfall pumps of various sizes. I use a super luft pump for air, and I have routed the air through air stones contained within 1/2" pipe for circulation in barrel #1  and [1/4' soaker hose intended for drip irrigation, wired in a spiral to several 24" disks of 1/2" coated wire mesh].  these disks are at the bottom of the biofilter, above the various pumps that distribute treated water: two for water return, one for solar heating, and one to recirculate the water to shower on top of the filter for a second pass.  The water is also aerated by water action as shown in my post to another forum here, as it enters the habitat.

I would use your 225 gallon tank if I had room.  It is said that it's better off to start with a big volume, and it would be easier for me to see and work with the fish.  My biofilter is a lot bigger than I have sen elsewhere in this site, probably because I am not using growbeds at this point.  But I am using 2 spools of springflow filter medium and  two two-inch thick x 24" diam  disk of layered scrub-pad type fiber mats as a pre filter.

Why redundant pumps?  One equipment failure in this system could be catastrophic.  The fish would quickly suffocate. And I have had pumps fail before.  If using pumps in parallel don't forget to use check valves, to prevent back flow when the pump is not operating. I try to have at least one or two total system volumes flow through the biofilter every hour. The recirculating pump within the biofilter is a cheat to get that, as well as returning the solar heated water upstream of the biofilter.

Why barrels?  They fit into my available space.  I would much rather have a larger tank.  A barrel might be good for smaller fish until they are too big to be eaten by the larger ones. And I have been wondering if I could convert an old hot tub to serve as a fish habitat- they already have pumps and bubblers.

wer winn: I am using one brass check valve and the rest plastic.  Check valves can fail if the water passing through is chunky and a particle lodges in the sealing surface just right. For this reason I want to use a fiber filter at some point to remove stuff like duckweed, plant detritus, food particles, and fish poop before it gets into the valves and the pumps.

I am setting up a 55 gallon plastic drum for a biofilter could anyone tell me what to put

in the drum not the expensive matting. any other material sand stones etc. thanks

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.

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.

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.

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.

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.

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.