One thing is for damn sure.
I'll be printing a sheet to pack with every fish I ship from now on !!!.
Low PH to Higher PH = No problem. If you have crappy water with a terribly low PH you need to ask your supplier what his PH normally is and adjust your Q tank before arrival.
If you're like most of the planet.. between 7 and 9 dont worry about it.
Hardness means nothing.
Low temp water to a warmer q tank = no problem, Toss them in !
If your water is colder than the bag.. float them a good long time... 30 minutes or so.
Mixing bag water with your water, is idiocy and can be highly toxic.If you have water in the bag with a likely PH of 6 -6.5 and mix it,50/50 with PH 8.5 - 9 ? Death.
Dipping a freshly transported fish in ANYTHING is idiocy.Dont salt the q tank either until you scrape for parasites.. Allot of goofs have their Q tank salted up at .3 or .5. Real cute if you find a bug and need to use Formalin...
Empty the bag into a bowl, pick up , or net the fish ( I do it by hand so I can look for problems), put them in the Qtank, cover it and walk away.
Take a peek the next day and toss a tiny bit of food in to make sure they are active.
Cover.
Walk away.
Day three toss a little food and if they react well ( like sharks) uncover them and " maybe" break out the microscope, if you see something that doesn't seem right.
If I dont " see" anything I might not even scope them until near the end of the quarantine period.
The most critical part of unpacking is to get them out of that nasty shipping water and into perfect water as quick as possible.
Mixing is a death wish and putting a warm koi into cold water is a death wish.
If somehow the bag water has a PH of 8 -9 ( like moving a fish across town) and you have a PH of 6- 6.8 or so You could have some bit of a problem and you should raise the PH up to 7.5 or so before tossing them in.. That would be an extremely rare scenrio but it happened to me once... years ago.
I move a couple fish ( 140 Jumbo's) from Lauderdale, that were in a pond with a PH over nine, and moved them to a tank ( 36 by 36 feet) with a PH of 6.8.. It didn't kill them but boy were they red and stressed out for a couple of days.. The big butterflies fins turned blood red in minutes..
King Kong.. ask Phil Maraccini about that weekend ...WHEW...