Digital Aquatics Lifeguard v2.0 Aquarium Monitor Alert emails can now identify which Lifeguard unit sent the email great for users with multiple Lif Significantly Improved pH and temperature measurement stability throughout the measurement rang Greatly improved pH calibration algorit Improved alert e-mail hysteresis - this prevents Lifeguard from sending too many e-mail alerts if t Improved long-term graphing performance.ul&gt; Easy to set up. Easy to use.i&gt; Lifeguards intuitive