If you want to confirm that pool water loss is due to evaporation and not a leak try the “bucket test”.
1. Fill a bucket about 3/4 full of water and mark the water level on the
inside of the bucket.
2. Place the bucket on the top step inside the pool and mark the pool
water level on the outside of the bucket.
3. The pool water must remain calm so turn off the circuit breaker at the
pool timer panel.
4. Leave the bucket in the pool for 24 hours. Make sure kids or animals
do not disturb the bucket or the pool water.
5. After 24 hours check the marks on the inside and outside of the
bucket and compared to the water levels.
6. If there is no loss or the same amount of loss in the pool and in the
bucket then the loss is due to evaporation.
7. If the pool level is down more than the bucket level then you may
have a leak in the pool. The difference between the two will tell you
how much the pool is leaking in 24 hours.
8. Remember, average pool evaporation water loss is 1/4″ per day.