I have these little brown dots on the bottom of my pool. Any idea what they are? Maybe tannin stains? We get a lot of leaves dropping in the pool, but the Kreepy Krauly runs every day, so none of them stay very long. Most of them are in pairs, about as far apart as the width of my thumb. Thanks!
TA: 150 (150 is where it stays red, 110 is where it starts turning red. Which is the right one?)
(edited with test results)