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/aquariumlore.blogspot.com Guppy owners welcomed to post pics of their guppies here. 

Did you mean Livebearer?Breeding: Lifebearer
It can go below 7.0 too, especially if you're going to go all the way up to 8.5. They can adjust to most any pH, as long as they are acclimated properly.Ideal pH: 7.0 - 8.5
64F seems a bit cold...they are tropical fish. I'd say 70F minimum.Temperature: 64-82 F (18-28 C)
Females actually always have gravid spots, pregnant or not. I'd say a darker gravid spot, perhaps?A pregnant female can be identified by the gravid spot (darkened area) behind her anal fin just posterior to the belly.
You might want to add in you can also use a breeder tank, let her give birth in the tank, or use a breeder net (cringe).To prepare for her delivery, keep the female in shallow (about 8 in.), aged water at 75 to 80 degrees F.