Fast chlorine loss
Could point to sunlight, contamination, high demand, insufficient output or a combination.
Clear-looking water can still be out of balance. Dull water can have more than one cause. Testing narrows the work.
Arrange a baseline testIllustrative indicators only. Target ranges depend on the pool, sanitation system and applicable guidance.

Blue Ledger's fictional workflow separates observation from action. The record should show the readings used, what was added and anything that needs follow-up.
Could point to sunlight, contamination, high demand, insufficient output or a combination.
May require a look at total alkalinity, aeration, dosing method and the pool's normal behaviour.
Water balance, filtration, circulation and suspended material all belong in the diagnosis.