Backyard Aquaponics
A place to discuss aquaponics

No not really. I was hoping to have it up and running by now but I've had a few interruptions. This year I'm back at uni and absolutley snowed under with work. I'm also saving money to go overseas next year and so I wont build it until I come back. I've spoken to lots of different people and got a few great ideas so it's all ready to go in my head. Please dont hold your breath waiting for updates. I've decided to just buy trout again this winter and let the SP and catfish freeze again.
I'm hoping that when I come back from overseas my wife will had over the pool, then I'll get a second panel and build a large heater for the pool

While my solar panel collects dust I thought of a cheep and easy way to build your own with parts from a car wreckers. Just get a large car radiator, encase it in a flat box (painted black inside) with a glass face, connect it up to a stainless heat exchanger using car hoses (can buy long lengths from Clark rubber), also connect the expansion tank to the radiator so that you can blow off any buildup of pressure and have this outside of the box so you can top it up if required, and use a car water pump (I think the old Magnas had an externally mounted 12V pump). If you wanted it bigger you could use more than one radiator. Would work out fairly cheep.

Using a car radiator is a good idea KEXIV.

For me, the most difficult part is finding an appropriate heat exchanger. (something reasonably inexpensive)

What are refrigerator coils made of? ie. the "snake" thing on the back of fridges.

Steel 99.9 % are a few are ally

Stainless steel? *raises eyebrows*

I think you'll find it's mild steel tube.. now lower your eyebrow .. you look silly.

H all,

Just beware that some car radiators have lead solder in them - at least the old ones do - not sure about the new ones. Would be ok if the water was kept seperate - and you use something like this heat exchanger to heat the water in the tank.

http://cgi.ebay.com.au/20-Flat-Plate-He ... dZViewItem

Although - you would also need to filter the tank water first to stop clogging up the Heat Exchanger.....

Regards,
Hamish

AND, ones 10 years old or more will have copper orbrass cores,,,another possible NO NO.
Modern radiators use Aluminium cores,,,,personally I think Aluminium is probably more dangerous than copper. Lead soldering,,now THAT I don't like.

Solution,.....,,not sure...

I have used a Sureflow model 2088-422-444 12 volt R.V. pump for three years on a solar H.W. application. It is widely available at about $70 U.S. It is a diaphram pump used often for pressure circulation systems. So it will lift at least 20 ft. and needs no priming. Flow for my solar hot water collector on the roof with the tank on the ground and passing thru a coil in an oil tank is about four GPM It will raise the oil temp to 130 deg in summer, just right for biodiesel. In winter I only get about 100 deg. F. I run this pump direct off an 80 watt PV panel which puts out 17 volts under load volts and about 5 amps. It starts up after sunrise and runs untill sunset, when cloudy it wont run. The only control needed is a valve on the discharge of the heating coil to regulate max. temp. thru the coil that I squeeze down in winter.
I use the same model pump on my sump to return water to the F.T. with only a 3 ft. head it runs to fast so I split the discharge and send some back to sump. This acts as a conttrol to keep the sump from going dry. The shureflo will tolerate some solids and some running dry.
I plan to run this pump to supply my solar H.W. collector returning to a storage tank and another to pump pull hot water into heat coils in the fish tank then return to storage. It wont handle over 140 deg. F. water so will have both pumps on the cooler side.

Sounds neat Spirit
Does that mean you will have 3 pumps in the AP system, or have I missed the GB side in the second pumping cycle?

Hi people. Are you all looking at running the actual fish water through your solar heaters? Wont it clog them up? Or is the idea to use a loop of clean water running through the solar heater and then dumping its heat into the fish tank using a coil of stainless tube?

If the latter is true - then perhaps adding some car antifreeze (glycol?) to the looped water will help in cold climates where it is likly to freeze overnight. I think this also helps raise the boiling point of the liquid and helps fight corrosion.

Or I might have this all wrong....

Hamish , some of the original ideas where pumping the actual fish-water through the solar system ..... then people declared copper POISON to fish ,, Copper is indeed poison at HIGH concentrations that would NOT occure in this situation. I was yelled down and snuck back into my corner , but still topping the water to my tanl thru COPPER pipes and having a Copper/ brass ornament IN my tank for the last 10 years,, BUT trust me I am wrong >

Thoughts have turned to plastic ,, found to be a no no ,, then Aluminium , this seems to be the general current thinking , BUT Aluminium is much worse than copper ( oh no , I'm gonna get flack again).

No people are talking heat exchanger\s,, yep the pump water through the solar is kept seperate so that nasty stuff won't get in ,, AHHHHH but what are the best heat-exchangers made of ???? Copper or Aluminium. I smile and watch.
Another point here is that a 'solar system" creates heat when you LEAST need it ,, so the heated water needs to be stored , kept warm and then pumped again.

The only usefull system I have seen on here , used the latent heat in a concrete driveway etc, now that is good thinking , heated block by nature that can be used after dark when needed.

Check your local power supply authority and have a look at the new water heaters. Their named SOLAR but they run off power and are basically a refridgerator running in reverse ,, they suck heat out of the air. Very efficient AND they can run on "off-peak" power at the times we NEED heat ( night/ early morning).

Nice idea re the heat pump.

I still really like the idea of the compost heater - but alas perhaps it wont generate enough heat... my thinking was that it is a 24 hour a day heat source unlike solar...

Might still give it a crack at this once my tanks arrive as I can make a simple compost tumbler out of a 200L black plastic drum ($20) for an experiment. At worst I am left with a tumbling composter to get rid of grass clippings and weeds

Concrete block heat storage is a good idea - just not for me as I currently rent so everything I put into my system needs to be portable and able to be moved when I eventually buy another house (not likely any time soon with the interest rate issues at the moment! I am glad I sold my house when I did!).

Anyway - back to thinking...

Stainless steel would be the ideal heat echanger for our systems wouldnt it?

Hamish

Propylene glycol is used in solar hot water heaters, using heat exchange units.

and PG IS deadly