3 days agoIf the ORP sensor is not older than 1 ½ years, a sudden drop in ORP can mean a high bacterial acrivity, much higher than before. Than can happen due to an organic rise and that’s why I used to keep a ORP meter years ago: to observe tendencies on ORP instead of the number isolated. Try to improve water quality by adding activated carbon and do a partial water change and see if the ORP reacts
