Add pool chemicals to water, not water to chemicals.

Yes, that order matters — and it’s the most important rule. Pouring water into concentrated chemical can cause a violent splash or fume cloud. Always slowly add the chemical to a bucket of water (if pre-dissolving) or directly into the pool with the pump running.

Read the label for specific instructions, but the general approach is the same for most chems: turn on circulation, add the chemical gradually near a return jet, and wait at least 15–30 minutes before testing or adding something else. Never mix different chemicals together beforehand — not even “just to save time.”

Your pool wants balance, not a chemistry experiment.