Backyard Aquaponics
A place to discuss aquaponics

Yep outback ,, spot on. I'm still to run a true test but I'm guessing 3 X 300 watt heaters can keep a well insulated tank at 23 C , with outside temps as low as 5-6C ( working on the lowest temps I get at my place). I'm waiting on delivery of a kilo-watt hour meter , so I can get a real cost calculation ( you don't know how many times the heaters are switching on-off etc).
The major problem is the grow beds and their heat sink effect. Several options here ,, no pump for overnight ( but then need a seperate bio-filter such as bio-balls), small pumpings , need to watch water quality as water building with nitrates.

If nothing else , all this is keeping my brain spinning

Chappo read the last few enterys in my system regarding temps[ interesting]

I have posted this before but here is an inexpensive $25 Differential thermostat for 12V - or you can get the delux version with a digital display for $75.

http://www.jc-solarhomes.com/MTD/12_vol ... ostat_.htm

Video of operation here:

http://www.youtube.com/watch?v=LiaQJh6BcmU

This guy also makes cheap solar collectors using PVC sheet and fabric - check out the details here:

http://www.jc-solarhomes.com/MTD/MTD_solar_heating.htm

And the videos here:

http://www.youtube.com/watch?v=BqHWolYUsw8

and here:

http://www.youtube.com/watch?v=NvROxccnGGI

The same guy has a lot of other videos about water heating - interesting.

I am thinking that I will insulate the sides and bottom of my tank and growbeds with foam sheet. And build a coldframe over each of the growbeds using PVC pipe or alloy and plastic sheet - bit like this drawing. Should keep the heat in with or without a solar heater.