Athosanswered grow question 6 years ago Brittle leaves, check. Interveinal necrotic spots, check. What you have is boron deficiency or to be precise, lockout due excess feeding. Unless you are using RO water or your tap water is really soft, and you need an EC/PPM meter to check this, there's no reason to be using calcium / magnesium additive, even more, 1 ml per liter is enough. Stop feeding, give it water only. Unless you get a pH meter and an EC/PPM meter you will be feeding blindly.