Glad you found the group blodger....
Sounds like your in the right place....
Check out this link to the Speraneo's system. they have a greenhouse that is very well designed and although they get snow in winter, they are able to grow tropical fish all year round purely thorough their careful design and building practice without having the enormous expense of heating...
I only mention this because thats an area that I think requires a lot of research and design work before constructing.. The idea of a wall in your greenhouse is good, but you may not want it to be a wall that keeps one area totally seperate to the other, with the heating only on 1 side... What will happen is that the greenhouse side will suck the heat out of the water when it pumps through the growbeds... However, with the whole structure well sealed. and a double skinned greenhouse side, with brick wall down the centre, including gaps top and bottom for air circulation. The wall will act as a large heat sink, helping to heat both areas.. The gaps in the brick wall for air circulation can of course be closed or opened as needed.
There's heaps of info on the net about passive solar design and time spent researching will save a lot of money in the long run.. During winter, the front glass section will gain a lot of heat, especially if it's double skinned...
So you breed fish then Blodger?
Joel
