This one’s pretty deep already, so I’ll try not to repeat what’s been said.
What made bromine “click” for me with the eagle ray was paying attention to combined load after heavy use. In my 375 gallon spa, if we’ve had 3 or 4 people in there and the bather load is high, the bromine number right after everyone gets out can look lower than expected. Not because the tester is off, but because bromine is actively oxidizing waste. If I test again an hour later with circulation running and no jets blasting air, it usually stabilizes.
I also noticed alkalinity plays a bigger role than I thought. When my alkalinity was drifting low, my pH would swing faster in hot water and the bromine reading felt less predictable. Once I kept alkalinity in a tighter band, both the pH and bromine readings looked more consistent test to test.
For me it hasn’t been a reliability issue with the tester. It’s more about understanding how bromine behaves in hot, aerated water. If you sample from mid depth, wait a bit after shutting off jets, and look at trends instead of one snapshot, the numbers usually make sense. Anyone else find that bromine feels more stable once alkalinity is dialed in?
