Aquarium Plant Health Guide

neon tetra fish in aquarium

Mineral deficiencies can be detected by observing the plants and their symptoms.

Magnesium, nitrogen, phosphate, potassium for example are mobile nutrients and calcium, iron are immobile.

Mobile nutrients can be moved within the plant to avoid a shortage while a deficiency in immobile nutrients has an instant effect on the plant.

Signs of plant deficiencies:

Symptoms Cause
Old leaves turn yellowish/ red Nitrogen deficiency
Old leaves turn yellowish/ red; Leaf loss and small dead areas Phosphate deficiency
Black/ brown leaves, plants die Excess phosphates
Yellow spots on old leaves and yellowish margins on younger leaves Potassium deficiency
Yellowish margins on young leaves with deformations Calcium deficiency
Yellow spots on old leaves while veins stay green Magnesium deficiency
Young leaves turn yellow Sulfur deficiency
Yellowing leaves starting from the tip then become transparent Iron deficiency
Yellow spots between the veins, margins and tips Zinc deficiency
Plant stays small slow or now growth white deposits on leaves (calcium) CO2 deficiency
Fish gasp for air on surface Excess CO2
Sluggish fish no plant growth Oxygen deficiency
Plants stop growing/ black roots Substrate problem

Additional considerations:

Carbon Dioxide (CO2)

A possible source for a CO2 deficiency can be a well aerated tank. Airstones or high surface turbidity can diffuse the CO2.

Excess CO2 can be a result of poor lighting (the better the lighting the easier, the CO2 uptake of the plants), or an over fertilization of CO2.

Substrate Problems

The substrate is either to loose or compacted. If agitated gas bubbles can be detected on the the surface. This is also an indication that the substrate is old and in need of replacement.

Water Temperature

Plants will stop growing and die off if the water is to cold. Higher temperatures will result in smaller leaves and larger gaps between these leaves.


Light is essential for photosynthesis. Not enough wattage or aging bulbs will stun the plant growth. Plants look weak with small pale green leaves. Plants closer to the light will be less effected.

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So i have a blehiri that has feep dark green veins and is showing signs of potas and iron issues. But the thing that gets me (recently moved so dont know if its a stress factor) is that new growth is coming in snarled up and crinckled and ive been dosing with sea chems full line aside from flourish advanced and to no avail. Ive been on a schedule and everything. And nothings changed. My bananas and all are doing great. I domt know whats going on. Any ideas?


Thanks for your information will help me and my plants to do good.. But one question remains that my carpet is not doing well but my background plants do have good growth. Why? I kept on bringing new carpet plants such as glossistigma, monte carlo, pogostemon helferi, nothing but they all melted in 2 to 3 days. Please help me.


My plants were turning black moved everything to a new 55 gallon tank now my leaves are turning yellow help ,not my first tank use to be able to grow lush healthy plants


Hi. My aquarium is a dirted planted 10gal., that after 2 yrs-finally took off since placed in my ‘sunny winter window’ it turned into a lush Aguascalientes garden! Temp is 70-75F. The Problem: Black, hard dots on leaves of Anubias- seems imbedded in leaves, no bumpiness tho looks as tho it is…tank gets direct morning sunlight & partial afternoon more indirect sun, ( dirted approx. 2yrs), 9 fish (four, 6 mm; four, 15mm all in tetra family; one, 10 mm, mini Otocinclus & a lot of ghost shrimp as in everywhere I look, a lot…) I frequently see that black… Read more »


Anubias are slow growing and the leaves are vulnerable towards algae. Black beard, green spot etc. Water flow should be increased and you should check on vitals to make sure neither phosphate or nitrates are available to excess. Keep in mind that slow growing pants have a much lesser need of fertilizers than fast growing plants. A 30 minute bleach bath often does wonders. Provide some shade for them and avoid to long or intense lighting periods.


Site looks great! Mobile works well. My plants are having the base dye and the plants keep floating up. I tested the water and it’s acidic. How do I add base? Hardness is high because I use well water since my tap is softened. I figured the iron in the water wouldn’t hurt. Should I go back to buying spring water?

Thilo @ Algone

You can increase the pH level by adding baking soda (1 teaspoon per 10 Gallon) This is a trial and error method. One teaspoon is a start and you can repeat on a daily basis until a more appropriate level is achieved. Crushed seashells have the same effect and are longer lasting. You can add those in a mesh bag (one cup for 50 Gallons). Again, this is trial and error. Monitor the pH and adjust accordingly. Once the pH is at the desired level, you can add the shells to the substrate, or keep the bag in the filter.


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