I lived on the Canadian side of the river/lake.
The glacial fed river where my cities tap water is now sourced from, originates on the side of a mountain, that makes up part of the Rocky Mountain range. It doesn't come from a bottle. lol
And yes, I did read what you wrote, you stated:
The fish if ok now will be fine. As was said not enough chloramine or chlorine in tap water if mixed will older water to do any damage. I too have been rinsing my media in cold tap water and have for years without any ill effects. Now I did an experiment and rinsed in warm to hot water and I did experiance a mini cycle. Also I agree that rinsing in old tank water is non sense.
For a starter the OP didn't mix anything with older water, his tank that contained these PB fry was filled with straight tap water.
In some parts of the country, no problem, in others, a 6 1/2 hour exposure time in chlorinated tap water would be a death sentence for most species of young fry. Forget about damage to gill tissue, the fish would be dead. The least of anyone's concern here should be BB die off, that part is an easy fix, but you can't un-ring the bell with regards to a fishes exposure to chlorine/chloramine. It's like saying that a "little" bit of second hand smoke won't harm an infant. At higher levels found in some municipalities untreated tap water can cause death within hours, at lower levels damage to gill tissue, and for those with very low levels perhaps 6 1/2 exposure will cause no harm.
That's the only point that I have been attempting to get across. You agreed with Water, Water was wrong to make such a wide sweeping generalization.
For many members here (such as those who have chlorine/chloramine levels near the EPA's max of 4 mg/l) rinsing their bio media in dechlorinated tap water, or their tank water, isn't nonsense, as you stated, it's the only way to go. Failure to do so will cause some or all (depending on their local disinfectant levels) of the bio-bacteria to die off. Free chlorine at even medium levels will kill most species of Nitrosomonas and Nitrobacter bacteria. How quickly, or how much, bacteria that free chlorine or chloramine will kill is highly dependant on numerous factors, such as the level of disinfectant residual coming out of the users tap, the water temp, pH level of the water, exposure time, etc. There is no study involving water treatment facilities that will state otherwise. In certain districts of the US some water treatment facilities that use chloramine can & often do have issues with controlling nitrifying bacteria in their systems, and some areas resolve that by running free chlorine at certain times of the year as chlorine is much more deadly to these bacteria than chloramine, which is partly made up with ammonia, which in turn feeds this type of bacteria. Again, a lot of this will depend on water temps, pH levels, disinfectant levels, etc.
This is not a simple case of black & white, everyone who reads this discussion could be dealing with different variables, not to mention the fact that the vast majority of members on this site most likely have no idea what level of disinfectant residuals are coming out of their tap. If you started a poll on this forum asking how much Seachem Prime needs to be added to 50 gallons of tap water, almost everyone will state 1 capful (5 ml), not realizing that doseage rate is for 4 mg/l chloramine, and/or 5 mg/l of chlorine. I've lost count how many times I have read that over the years, with no one enquiring as to the OP's type or level of disinfectant being used in
their tap water.
So yes Alan, I understand that this is what you DO, my point was simply that for those who have to do things differently due to their local conditions, there may be a very valid reason for that, and it isn't nonsense.
HTH