Aquarium plants nutrient deficiency

A nutrient deficiency can create big problems in a planted aquarium, sometimes a nutrient deficiency is caused by an excess of another nutrient.
It is very difficult to provide the exact amount of nutrients because the nutrients level is difficult to measure.
The easiest way to observe if you have a nutrient deficiency is to study the health of the plants.
Aquarium plants nutrient deficiency can be observed in the following ways:
• Color of the leaves, in case of nutrient deficiency leaves are yellow or white
• Shape of the leaves, nutrient deficiency leads to misshapen and stunted new leaves.
• Structure of the leaves, deficiency creates holes in leaves.
Fast growing plants are a good indicator of nutrient deficiency because this type of plants does not have high reserves which means that soon after the nutrient deficiency has been installed plants will show nutrient deficiency symptoms.

Phosphate (PO4)

Recommended Phosphate level:  0.05 -1.5mg/l  
Phosphate is an important plant nutrient and in nature can be found in very low concentrations about 0.01 mg/l.
In freshwater aquariums the main source of Phosphate are the fish food and fish waste. When the optimal phosphate level is exceeded algae will start to multiply and soon you will see algal bloom. Algae can store large amounts of phosphates allowing them to grow further even if the level of phosphates has decreased until the recommended level.
In many aquariums with few fish and many plants there is a risk of phosphate deficiency which means that older leaves are yellow and quickly the leaf will fall off. In some cases green spot algae can be observed on leaves.
Phosphate deficiency looks pretty much like nitrogen deficiency.
Remedies for Phosphate deficiency:  Easy Life Fosfo, Seachem Flourish Phosphorus, MICROBE-LIFT Phosphorous

Magnesium (Mg)

Recommended Magnesium level: 5-10mg/l
Magnesium is a very important macroelement and is necessary for plant growth.
Symptoms of magnesium deficiency: Dark veins and leaves are turning yellow.
Magnesium deficiency has almost the same symptoms like iron deficiency and can be easily confused, the only difference is that at Magnesium deficiency the yellowing between the veins of the leaves is greater. New leaves have the same magnesium deficiency like old leaves.
Magnesium deficiency is stopping the plant growth and until the magnesium is provided plants will stagnate. To measure the magnesium consumption in your aquarium you have to make test daily.
Remedies for Magnesium deficiency: JBL Pro Scape Mg Macroelements.

Carbon Dioxide (CO2)

Recommended Carbon Dioxide level: 20-25mg/l
Carbon Dioxide is a very important nutrient and in most cases it is the limiting factor in overall growth. In a freshwater aquarium a level of CO2 below 20mg/l will lead to problems because it is limited the photosynthesis.
Symptoms of carbon dioxide deficiency: White deposits on leaves, Young leaves are twisted or twisted, Yellow Leaves, Algae on leaves, especially when it comes to talking about algae on leaves I mean BBA.
CO2 deficiency can be overcome by using a CO2 system with a PH Controller, in this way you plants will win the fight against algae.
Please remember that for a healthy aquarium you need not only CO2 but also Light and Nutrients.
Remedies for Carbon Dioxide deficiency: CO2 system, Liquid CO2.

Manganese

Manganese it is a nutrient that is absorbed by plants through leaves and roots.
Manganese can be found in tap water and that is the reason why Manganese deficiency is not very common in freshwater aquariums.
All universal plant fertilizers contain Manganese and when you add fertilizers in aquarium you add also Manganese in this way you are sure that your plants will not suffer Manganese deficiency.
Symptoms of Manganese deficiency are: Leaves with yellow spots, Holes in leaves.
Remedies for Manganese deficiency: All liquid fertilizer contains Manganese.

Nitrate (NO3)

Recommended Nitrate level: 5-25mg/l
Nitrogen (Nitrate – NO3, Ammonium – NH4) is an essential nutrient for plant growth and is provided to plants in different forms Nitrate (NO3) and Ammonium (NH4). The nitrate level is influenced by the number of fish, or few water changes, for example too many fish in an aquarium will increase the NO3 level.
 In aquascaping where are few fish and many plants Nitrate deficiency can occur and in this situation nitrate must be added separately. You must be aware that high levels of nitrate in combination with phosphate will promote algae growth.
Symptoms of Nitrogen deficiency: Old leaves are yellow, Young leaves are light green.
Remedies for Nitrogen deficiency: Seachem Flourish Nitrogen, Easy Life Nitro, MICROBE-LIFT Bloom&Grow Nitrogen.

Potassium (K)

Recommended Potassium level: 5-10mg/l
Potassium is absorbed very quickly by plants and compared with other macroelements potassium is consumed by plants in larger quantities. The amount of potassium used by plants increases with the light intensity, for example for aquariums with illumination of 1W/l or above the recommended potassium level it is around 10-20mg/l.
Symptoms of Potassium deficiency: Leaves are yellowing at edges. Brown dots on leaves, in time the size of the dots increases.
Remedies for Potassium deficiency: Seachem Flourish Potassium, MICROBE-LIFT Potassium.

Iron (Fe)

Recommended Iron level: 0.05-0.02mg/l
Iron is a very important micronutrient and it is consumed by plants in the ion form.
Fast growing plants are a good indicator for iron deficiency because new leaves are pale and the veins are green.
New leaves are pale because the chlorophyll synthesis is reduced in case of iron deficiency.
Symptoms of Iron deficiency: New leaves are yellow with green veins.
Remedies for Iron deficiency: Dennerle E15 FerActiv, EHEIM Ferrous fertilizer, Easy Life Ferro, Seachem Flourish Iron, MICROBE LIFT Iron.

Calcium (Ca)

Recommended Calcium level: 20-30mg/l
Most aquariums will never have Calcium deficiency because Calcium is present in sufficient quantities in tap water.  
Symptoms of Calcium deficiency: Misshapen and stunted new leaves.