Re: Aging water for partials. I do this routinely, have done for some time, and have absolutely no intention of discontinuing the practice. I use the Python to remove old water from the tank, refill with aged heated and chlorine-free water from the reservoirs (meaning that I do not have to add thio and slime coat garbage to my tanks), then refill the reservoirs -via Pthon - to be available again in 48 hours. I much perfer to not to add materials to my water which I do not need and which do nothing needed for my tanks or fish.
That is personal choice - but it ensures that I cannot make mistakes in addition, as there are no water treatments required, and the water temp is known to be correct before it is pumped. To me it is cheap insurance and cleaner tank water. For various reasons many do direct addition, and that can be done safely, but to me it not quite the same as de-gassed, heated, aged water. BTW, I'm running hundreds of gallons of water.