Yes #1 you are correct about the PH!!
To prepare a proper freshwater dip, take either dechlorinated tap water or demineralized water (RO or DI), aerate for an hour to maximize dissolved oxygen, heat to match the temperature of the dip water to that of the tank water, and then add buffering compounds to match the freshwater pH to your saltwater pH. The aeration should continue throughout the dip. It is crucial to match temperature and pH and to maximize dissolved oxygen. Most people that experience problems with freshwater dipping have made an error in these critical parameters.
The recommended duration of the dip varies from author to author because different species of marine fish tolerate freshwater to different degrees. Generally speaking, any dip less than two minutes is useless. Many fish will easily tolerate five, ten, even fifteen minutes or more. The least tolerant fish are wrasses, lionfish, pufferfish, drumfish, hi-hats, jackknives, firefish and many of the scaleless fish as a rule (Calfo, pers. comm.). I also choose not to dip lionfish, foxfaces, or any other venomous fishes because I don't want a flying torpedo of spines to come shooting out of a dip bucket at me. A lionfish has stung me before, and it is not an experience I ever wish to relive
I spoke to a lot of beginners & they spend so much money on the set up & etc, they use chemicals instead of RO/DI....
I bought the RO/DI right after my tanks & setthem up....But I had an endless money...