PH should be high, just like other cichlids they prefer alkaline. I keep my oscars at about 8 to 8.2. That also helps keep ammonia/ nitrite down. Temperature is up to you, the higher the more active and hungry. The lower the temp the less active, less they will grow. I keep my oscars at 78-80 degrees. Also higher temps keep disease away in any fish. Make sure you don't feed your oscars too many rosies and/ or gold fish. unlike other cichlids they can't use that much protien in their diet (no matter how much they love to chase them). Buy them guppies instead, it may be more expensive, but they won't get hole in the head disease.