Is it possible to...

Keep us updated! (I'd definitely watch the Rams closely)
 
The acclimation to the new water can be done in a few hours without a hitch. So doing it as 10-20% every couple of days would be even safer than that. In other words, you are not facing any challenges, problems or even worthwhile concerns. Just do it.
 
I don't understand the rush with daily water changes. Why not just use tap water in your regular weekly changes. That would give them weeks to acclimatize.

Stupid question - what's a GBR?
 
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