If this measurement is unknown:
- Use a piece of duct tape, or a pencil, to mark the exact water level on the faceplate of the skimmer box, or if necessary, on the pool wall near the stairs or ladder.
- Wait 24hrs, re-mark water level and use a measuring device, like a ruler, to calculate the rate of loss (inches/24hr).
- Label your markings with date and time.
- If this result is inconclusive, leave original markings and repeat this process as needed. Please leave all labeled markings on the pool for the diver to observe.