Could not enough calcium in water/feed be causing calcium deficiency?

Using RO, distilled, or filtered water. Growing in coco coir. Not using Cal-Mag supplement. Fix: Add Cal-Mag at 3-5 ml/gal every feeding Coco + RO water ALWAYS needs Cal-Mag — mandatory

Could ph too low for calcium uptake be causing calcium deficiency?

Runoff pH below 6.0 in soil. Calcium is in feed but not absorbing. Fix: Raise water pH to 6.3-6.5 (soil) or 5.8-6.2 (coco) Use pH Up to adjust

Nutrient IssuesSerious

Calcium Deficiency in Cannabis

Calcium deficiency is extremely common in coco coir grows and when using RO or filtered water. It shows up as small rust-colored spots and distorted new growth.

What it looks like

●Small rust-colored or dark-brown spots on young leaves
●New growth may look twisted or distorted
●Hooking leaf tips or necrotic spots
●Common in the upper part of the plant (calcium is immobile)

Quick diagnostic checks

1Coco + RO water? Add Cal-Mag TODAY — it's not optional

2If spots appear, dose a heavier Cal-Mag and check pH

Causes ranked by likelihood

1. Not enough calcium in water/feed

Most common

Signs

●Using RO, distilled, or filtered water
●Growing in coco coir
●Not using Cal-Mag supplement

Fix

✓Add Cal-Mag at 3-5 ml/gal every feeding
✓Coco + RO water ALWAYS needs Cal-Mag — mandatory

2. pH too low for calcium uptake

Common

Signs

●Runoff pH below 6.0 in soil
●Calcium is in feed but not absorbing

Fix

✓Raise water pH to 6.3-6.5 (soil) or 5.8-6.2 (coco)
✓Use pH Up to adjust

⚠️When to worry

Cal deficiency during flower can cause bud defects and lower yield. Fix promptly.

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