Name: Anne Summerville, SC (Zone 8a) Only dead fish go with the flow!
A cheap easy way for passive solar heating is to paint 2ltr soda bottles black and fill them with water. I use these in my greenhouse and actually sit plants on them that are especially sensitive to cold .. they manage to keep the soil temperature about 5 degrees warmer.
Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.
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