Plant Deficiencies

Nutrient deficiencies tend to affect high light and high CO2 tanks more as the plants use up available nutrients quicker. It is very hard to measure a lot of the nutrients which is why the Estimative Index method of dosing works so well by providing all of them to a small excess. Even so there are times when something is not quite right with some or all of the plants. Trying to identify which nutrient is lacking can be a difficult process at times as one deficiency can mask a different one. The first thing to look for is whether the deficiency is affecting new leaves or old leaves. Plant nutrients are considered to be mobile or immobile. Mobile nutrients can be reclaimed from old leaves and used to produce new growth, so problems will show mainly in old leaves. Immobile nutrients cannot be moved from the older leaves and so new growth is then affected.

The following table provides a good starting point to identifying plant deficiencies but be aware that with high light not everything is quite so straight forward. For example limiting nitrogen or phosphorus is supposed to effect old leaves, but I have found the opposite to be true in that new growth can sometimes be stunted. This is possibly due to the faster uptake of nutrients under high light.

Element Leaves Symptom
Boron New Dead shoot tips and side shoots
Delicate stems
Similar to calcium deficiency
Calcium New Distorted leaf growth
Twisted and short roots
Yellow leaf edges
Carbon Dioxide New Slow growth
Distorted leaf growth
Possibly calcium deposits on leaves
Copper New Dead leaf tips
Iron New Pale growth of new leaves
Leaves can become brittle
Yellowing of leaves
Magnesium Old Yellow patches with veins remaining green
Similar to iron as it prevents plant from absorbing iron
Distorted leaf growth
Manganese New Dead yellowish tissue between leaf nerves
Molybdenum Old Yellow spots between leaf nerves
Brown edges
Inhibited flowering
Nitrogen Old Stunted growth
Leaves turn yellow and die off
Slight reddening of leaves on occasions
Phosphorus Old Stunted growth
Darker leaves
Poor root growth
Potassium Old Pinholes appear which slowly enlarge
Yellow patches
Curling leaves
Stunted growth
Sulphur New Leaves turn yellow and die off
Zinc Old Yellowish areas between nerves starting at the edges

I haven't included light in the table as it is not really a nutrient in the true sense of the word. It does however play an important part in plant growth. Poor light will create spindly plants with small leaves. Leaves often fall off towards the bottom leaving it bare.

This page was last updated 13th September 2007