NYT is spouting every headline they can imagine to shift votes toward Trump, and not just lately. Their entire editorial focus is to cast confusion on Democrats’ prospects. They should be recognized as firmly partisan and no longer serving a journalistic purpose. Unfortunate, but that’s the times in which we live.

Swimming pools are normally constructed empty. They were withstanding surrounding soil before they were filled, and concrete strength increases with age (for about 90 days, typically). On the other hand, a sunken structure like a pool that is roofed over, becomes a “confined space”. Unlike a typical structure, heavier-than-air gases cannot escape from the pool. Such gases could originate from the drain system or flow from leakage outside the pool area. For examples, leaking propane or various gases from sewer lines in the vicinity. A sunken greenhouse would almost certainly be a building code violation for that reason. If you build it, ventilate it by means both active and passive and do not enter if you can’t verify that ventilation is working.

Declining birth rate is not a problem that requires fixing, it is a mercifully wise collective decision by intelligent creatures who’ve become educated and aware enough of their place in the biosphere to recognize the destructive effects of their own overpopulation. The idea that declining birth rate is decidedly NOT economic - lower birth rate does not arise among the poor and uneducated in the world.

There is no problem in today’s world that would be mitigated by increasing birth rate. I live in a region where there is a burgeoning elderly population and sometimes people say - we need more young people in this economy! But that does not mean that having more babies here is any help: by the time they are adults, the wave of excess elderly people will be gone. Economic crises are far more immediate than generational solutions - if a region lacks workers, economic forces are more effective to relocate workers than biologically growing new ones. Of course, governments often fail to anticipate needs and adjust migration policies in a timely way, or housing policies, or other such issues that create barriers contrary to the economic forces.

top slab is about 230 or 240 pounds. Wood base is only about 15 or so; light. I made no attachment between the concrete and the wood - just gravity.

Engineers describe heat transfer with a “heat transfer coefficient”, and the rate of heat transfer is this coefficient multiplied by the temperature difference. So you can calculate what the heat transfer coefficient must be by measuring room air temperature initially, water temperature initially, and then running your system for a little while and measuring the room temperature again. The smaller room area you can cool the more accurate this will be. You will need to look up heat capacity and density of air (easy to find), and the temperature change of the air with the volume of the room and the temperature change will together give you an amount of heat you removed from the air to the water. Simple!