Letting tap water sit overnight removes chlorine, but many cities now use chloramine, which does not evaporate and keeps knocking back the soil microbes with every watering. For an auto in living soil or with mycorrhizae added, that damage shows up as weaker growth by week four with no clear cause. A note on https://turboautoflowerseeds.com lists which treatments remove it, and a pinch of ascorbic acid per bucket is the cheap fix I settled on. Bottled or filtered water is overkill for a plant in plain coco with synthetic feed.
