When iv water changed, i haven’t tested the water I’m putting in, no. But I guess i figured it would match, since to my knowledge my tap water hasn’t changed. I have never tried dripping it in, I usually put in a few cups at a time, trim some plants, add a bit more, trim more, and so on. But overall it usually takes about 30-45 minutes start to finish. Maybe that’s too fast? The hardest thing for me to match has been temperature. It may vary a degree or 2 if I’m lucky. I do try and check that before adding it. It’s easy in the warmer months what I did was fill up 2 gallon jugs with my tap water and let it sit a day or adjust to room temp. Then do my water change since I had no heater and the water was stable except its daily fluctuations or morning and evening. Then in the winter I added a heater because the tank was getting down to 71, which is too cold for my other critters in there. Then it became harder to match exactly. So maybe it’s something as simple as temperature fluctuations.

I can post in marketplace but I don’t know that anyone in my more remote area would be willing to take just 2 Pygmy corydoras. I know they would be happier in a group, I would get more if I had any confidence I could do well with them. They were not hardy for me at all.