Long ORP is a more precise ORP (Oxidation-Reduction Potential) reading taken periodically by your Crystal Water Monitor.
To understand why we do this, it helps to know how ORP is normally measured. ORP measures the sanitizing power of your water in millivolts (mV). ORP sensors need time to equilibrate with the water before they settle on an accurate value. Getting a fully stabilized ORP reading can take up to 20 minutes. Because the monitor runs on AA batteries, performing a full ORP reads would drain the battery too quickly.
To balance accuracy with battery life, Crystal Water Monitor uses a combination of the fully stabilized ORP measurements and shorter ORP measurements. The fully stabilized measurements are taken periodically and used as a reference to estimate the true ORP from the short measurements. This gives you a frequent, consistent view of your sanitizer levels throughout the day.
If you are testing Crystal Water Monitor, you can find the last fully stabilized ORP reading on the water report screen for an apples-to-apples comparison with other measurement devices