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https://www.icmag.com/ic/picture.php?albumid=52962&pictureid=1267887View Image
This is the worst one, how can I stop this?
Deff looks to be low PH. Check your runoff. my babies looked exactly like that last week. Ran 6.5 through it until the ph went up ot about 5.7-.9 from 5.0, and they bounced back two days later. Happened to me because I let it dry out for one day in coco, and I'm assuming salt built up in the medium.