Thanks guys for the input, but I have to ask some more questions concerning this. Why are we adding additional water in barrels to heat, when we have a AP system full of water already? I know traditionally, greenhouses did this because they were not AP systems, so they had no large mass of water to heat and had to add it, but we have a large AP body of water already? With Green house space running on average of $50.00 per square foot to construct, each barrel is taking up approximately 4 square feet, which means each barrel is costing $200.00 in non-productive space. This would mean if we add 10 barrels we have to construct $2000.00 worth of additional green house space, just for the barrels. Of course we could offset that, by building grow beds above it? But now we are adding extra cost to support all that weight that normally could be supported by the ground?
When it comes to heating the soil around the fish tank, I go back to my original question. What are we, in the end, trying to heat?? The AP water? So why not heat it directly with a heat exchanger?? A heat exchanger in the FT or sump tank has the advantage of directly heating the water, therefore there is no transitional loss of heat to the soil. The other advantage is, if there is a problem we can easily access it for repair, no so easy if the piping is buried in the dirt under and around the tank.
Look guys do not take this the wrong way. I do appreciate the input. I am just trying to fully understand what the benefits are to these different methods, compared to a simple heat exchanger directly heating the AP water?? Working out problems here in our discussions is cheap compared to constructing something, then finding out it is not as good as we thought.