5 of the 8 shrimp have died in the last 4 days. One of the remaining three looks great, another looks not bad but not great, and the third just hasn't died yet. I think the two better ones are a male and female, the better one being the female, so hopefully they reproduce as I think shrimp born in the tank will do a lot better.

IDK why they decided to all die now, other than that it looks a lot like what happened before: they seemed to be developing the same white-on-the-outside problem. Also they seem to be dying in order of size, the first one being so small vs. the others that I was surprised that I had any that small. IDK where it'd been but I was used to seeing larger ones.

The tetras are all still alive but, while they were friendly for a few days before I started slowly dripping in the rain water at about a gallon a day, they don't really get along with each other anymore. I stopped doing that a few days ago, as I want to try the "leave it alone" approach and see what happens. One of them had a hair stuck in its mouth yesterday. I tried to get it out but after 5 minutes decided I was never going to catch it. The hair is gone now, I hope it got it out vs. swallowing it.

After adding all of that rain water, I think the pH is down to 7.4. At first it didn't seem to have made a difference, with the meter always reading 8.4 when I put it in the tank, but then I thought about how it can't read distilled water due to lack of ions, so I took a sample and added some salt and that made the meter read 7.4 instead. ...but it's not like the tank water is pure, so IDK that that should have made a difference.

Overall I'm starting to feel like pH is some kind of BS. Does it even have an application outside of saying "this water good" and "this water bad?" Like, length and mass have applications because those things aren't BS, and if pH is BS then it's not going to have any real non-subjective use.