i have been wanting to make a compost bin cause we have alot of materail that we winde up throughting out in the sumer. i dont have much room to put one and it has to be concealed. the idea i have is since i want to put up a pergola, to buildit under the pergolainside of a liner coated with an insulated cement, use a trash pump to keep it mixed up,and an areator to keep it oxegenated. i woudl pump in water when nessicary from my pond as it will be high in nitrates, this will also help me keep nitrate levles lower in thepond. i am concerned about venting the gas, and i want to tryand keep as much heat in as possible. im considering the idea of heting my pond with sloar heat durring the winter. whati have thought about doing is useingthe compost slurry as a heat exchanger and heat storage. pumping heated water from the slor collecter through coils in the slurry and then pond water through another set of coils to the pond... i only want to heat the pond to about 40 degrees any more then that and the fish and plants would not go dormant for the winter and that could injure them both. i like the slurry idea for the reasons of it could be left to mix its self constantly and then the slurry could be diverted and "sprayed" on to the garden beds.. any ideas or experiance with this?