There are 1 or 2 plants showing these brownish spots on a few leaves. Some of the spots have grown into small brown patches.

These plants are 5 weeks old and have been in 12/12 for 1 week. They are watered with tap water treated with vitamin C (for chloramine removal), so I doubt there's an actual calcium/magnesium deficiency in the water. It's possible the pH swung pretty low for a short period (1-2 weeks).

What do you think these spots are caused by? I'm certain they aren't spider mites as I've seen the damage from them and this is different...

Also, do you have to worry about calcium/magnesium deficiencies in tap water if pH is good? If you're running about 150 ppm hardness then you should have enough of BOTH calcium and magnesium, right? Can't you lock out magnesium somehow by having too much calcium or vice versa? Can someone explain this to me?! Also, how can I verify and resolve?
lampost Reviewed by lampost on . Are these brown spots cal/mag deficiency? There are 1 or 2 plants showing these brownish spots on a few leaves. Some of the spots have grown into small brown patches. These plants are 5 weeks old and have been in 12/12 for 1 week. They are watered with tap water treated with vitamin C (for chloramine removal), so I doubt there's an actual calcium/magnesium deficiency in the water. It's possible the pH swung pretty low for a short period (1-2 weeks). What do you think these spots are caused by? I'm certain they aren't spider Rating: 5