SimonL- have you ever seen how dishes breeders do water changes?
Discus breeders often do huge water changes, but their fish are used to it. Many also split the water 50/50 with RO to lessen Ph and hardness.
If your method is true, then why don't breeders send 50% of the tank water when they ship a fish half way around the country?
Second thing, the ph of a fish in a bag drops dramatically during shipping from a combination of excreted waste and CO2. When fish arrive, it is necessary to re-acclimate them slowly to the desired water. This causes massive shock to the fish, often stores loose whole tank fulls of fish during the acclimation. This is exactly the thing I'm suggesting the OP avoid. A responsible fish keeper would try to match the ph of the shipment to the fishes. If you get a shipment of fish form Peru, coming in soft water, and put them in a tank of 99% new tapwater, you'll likely lose the whole batch.
Also, if the person is moving 5 minutes away, depending on lights, wouldn't that lead you to believe that source water is the same?
Source water is different from tank water. When you have an established fish tank, the Ph and hardness change (usually by lowering). Unless you have a constant drip of new water, your tank isn't going to be the same, nor should it if you have softwater fish.
Last but not least, imyou really don't think that water chemistry doesn't change with flooding and rainfall then arguing with you about to transport fish is not worth it.
So, given your total lack of evidence to support your statement, you feel I'm not worth arguing with? "Duh, cause it is" is not a valid backing for your point. You stated that water ph and hardness in the wild dramatically changes within hours on a frequent basis. I'm not saying you're wrong, simply that you provide some evidence.
It seems as though oh believe that since that's how you do it at a fish store makes it right since you e been doing it that way for x years
Correct. I have worked at several LFS for 10 years. I've moved large amounts of tanks. I've imported and acclimated tens of thousands of fish. I have experience with this. Hence why my way is better.