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Archive for January, 2010

A maintenance programme is an important part of successful aquarium management and regular water changes are in important part of this routine. The big questions are ‘how much and how often’?

Filtration systems may help to reduce pollution in a tank but they will not solve all the problems. While a tank may look to be in good condition with clear water and healthy fish it could be the case that the fish are becoming acclimatised to a slow but steady rise in levels of toxicity. This is often the case when everything has been going smoothly for weeks on end and then suddenly everything starts to go wrong.

In all aquariums substances will be produced, which if left, become harmful – to fish and to plants.
These substances will appear from various sources. Dead or decaying plant materials produce toxins. Uneaten fish food will result in phosphates being produced and fish excrement will produce nitrates. Both of these elements are required by plants but there is no way of knowing how much there is. The fact is that if nothing is done, the level of toxicity will steadily increase.

The solution is to carry out water changes – where a percentage of the water in the tank is drained away and replaced with fresh water.

The following graphs show the effect of changing different amounts of water and at different time intervals. Without water changes the toxicity levels will increase indefinitely but do a regular water change and the toxicty will level off.
In order to keep toxicity to a minimum it is better to carry out large water changes on a regular basis. This is particularly important if you have a high fish population (or messy feeders).
If you follow the EI doseing system to feed your plants then it is important to change the water – 50% or more on a weekly basis.

What is Sulphur?

Sulphur is one of the molecular building blocks for a number of proteins, hormones and vitamins, such as vitamin B1. It appears in many important plant tissues, such as in seeds and in cellular moisture. In the form of sulphate, sulphur fulfils an important role in the water equilibrium in the plant, as well as in the soil.

For hydroponic gardening, all the nutrients a plant needs are given while watering. As a result of this, fertilisers designed for hydro culture contain high concentrations of lime and sulphur. In order to prevent calcium and sulphur from reacting with each other so that poorly dissolvable gypsum is formed, the two materials are kept separate by manufacturers by means of “A” and “B” packaging.

Symptoms of a deficiency

It would be expected that the earliest symptoms would first appear as a light green colouring in the young leaves. However, in practice, we’ve repeatedly noticed that the symptoms were the most obvious in the older leaves.

Development of a deficiency

• Light green coloration in one or more large/older leaves.
• Strong purple coloration in the leaf stems (due to the production of anthocyan pigment).
• More leaves change colour, and the light green colour changes in places to deep yellow.
• When the shortage is extreme, the plant has lots of deep yellow leaves with purple stalks and leaf stems. Additionally, growth and flowering are inhibited.

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Reasons for a deficiency

With outdoor cultivation, a shortage of sulphur rarely occurs. In potting soil, a sulphur deficiency can occur when the pH is too high, or too much calcium is present.

Solutions for a deficiency

• It is easier for the plant to take up sulphate at a lower pH level. Check the pH of the medium, and lower it if necessary with sulphur, saltpetre, phosphor or citric acid.
• When there is a deficiency, the best thing to do is add sulphur in an inorganic form with a fertilizer containing magnesium, Epsom salts for hydro, and kieserite in soil.
• If organic fertilising is preferred, composted mushroom fertilisers, and fertilisers from animal sources can be used. Sulphur is only absorbed by the plant in the form of sulphate, which appears in the soil during decomposition of organic sulphur compounds. This process takes time. Therefore preventative work is advised, along with a well composted fertiliser.

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Reproduced with kind permission from Canna-UK

What is Calcium?

Calcium occurs throughout the entire plant. It is used for many processes in the plant, however, calcium is most important for the growth process. It has a regulating effect in the cells and contributes to the stability of the plant. Plants have two transportation systems at their disposal: the xylem vessels and the sieve vessels. Most nutrients can be transported via both systems, however, for calcium this is not possible. Since calcium can be transported almost exclusively
via the xylem vessels, it is an element that deposes of little mobility within the plant. It is, therefore, important that a sufficient amount of calcium is always available in the root environment, so that it will be continuously available for absorption by the plant.

Symptoms of a deficiency

The older, larger leaves just above the bottommost ones will show the first symptoms. Yellow/brown spots occur, which are often surrounded by a sharp brown outlined edge. In addition, the growth is curbed and in serious cases the tops are smaller than normal and do not close.

Development of a deficiency

• The symptoms often appear quickly; within one or two weeks of the first spots being visible on the older leaves. The spots usually start as small, light brown specks that increase in size over time.
• After two weeks, the older leaves show ever increasing spots and the spots also often appear at the edge of the leaves, as with a potassium deficiency or with scorch symptoms. The spots have a sharp outline and do not originate exclusively at the edge of the leaves. A lag in development is often already noticeable within a week.
• Sometimes the growing points will wrinkle up and around the fruits you will find thin, small leaves that are not spotted.
• The older leaves die off slowly and yellowish cloudy spots may appear around the necrotic spots. The older the leaf is, the more serious the symptoms are.
• The flowering is also hindered and slowed down. Fruits stay small.

Reasons for a deficiency

• Culture on calcium fixing soil.
• An excessive amount of ammonium, potassium, magnesium and/or sodium in the root environment. The absorption is curbed mostly by ammonium and least by sodium.
• Problems with the evaporation caused by an excessively high EC value or by excessively high or low relative humidity.

Solutions to a deficiency

• If the EC value of the substrate or the soil is too high, it can be easily rinsed out with pure and if necessary acidified water.
• Additional calcium can be applied through the nutrient solution by means of liquid lime fertilisers such as a calcium nitrate solution. With an excessively acidic soil, lime milk can be used to increase the pH.
• Use the appropriate soil that is not too acidic. Acid soil often contains insufficient amounts of lime. Good potting soil and Coco substrates are already limed.

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Reproduced with kind permission from Canna-UK

What is magnesium?

Magnesium is an indispensable element. In plants, it represents a building block for chlorophyll (leaf green), and therefore, it is essential for photosynthesis. At the same time, magnesium plays an important role in the energy transfer. Together with calcium, it is also a component of tap water, influencing water hardness. Inorganic magnesium fertilisers are produced using the same bases that are used to produce potassium fertilisers.

Symptoms of a deficiency

When there is a shortage, the leaf green in the medium-old leaves under the flowering top will be broken up, and the magnesium will be transported into the young parts of the plant. This breakdown is visible as rusty brown spots and/or vague, cloudy, yellow spots between the veins. A slight shortage of magnesium hardly affects flowering, although the development of the flowers makes the deficiency symptoms worse.

Development of a deficiency

• Signs of a deficiency first appear around the 4th-6th week. Small, rusty brown spots and/or cloudy yellow flecks appear in the middle-aged leaves (under the top of the plant). The colour of the young leaves and the fruit development are not affected.
• The size and number of rust-brown spots on the leaves increase.
• The symptoms spread out over the whole plant, which looks ill. When the shortage becomes acute, the younger leaves are also affected and flower production will be reduced.

Reasons for a deficiency

• A very wet, cold and/or acidic root environment.
• A high quantity of potassium, ammonia and/or calcium (for instance high concentrations of calcium carbonate in drinking water, or clay soils rich in calcium) in comparison with the quantity of magnesium.
• A limited root system and heavy plant demands.
• A high EC in the growing medium, which hinders evaporation.

Solutions for a deficiency

• When a shortage is diagnosed, the best thing to do is spray with a 2% solution of Epsom salts.
• Fertilisation via the roots: Inorganic: Epsom salts on hydroponics or kieserite (magnesium sulphate monohydrate). Organic: composted turkey or cow manure.

Recovery

Rectify the possible causes: In soil, when the pH is too low (less than 5), use magnesium containing calcium fertilisers. On hydro, temporarily apply a nutrient solution with a higher pH (6.5). When the EC is too high, rinse and/or temporarily feed with drinking water only. When growing indoors, keep the root temperature between 20 – 25 degrees Celsius.

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Reproduced with kind permission from Canna-UK

What is Potassium?

It is necessary for all activities having to do with water transport and the opening and closing of the stomas. Potassium takes care of the strength and the quality of the plant and controls countless other processes such as the carbohydrate system.

Symptoms of deficiency

Evaporation is reduced if there is a shortage of potassium. A consequence is that the temperature in the leaves will increase and the cells will burn. This occurs mostly on the edges of the leaves, where normally, evaporation is highest.

Development of a deficiency

• Tips of the younger leaves show grey edges.
• Leaves turn yellow from the edge in the direction of the veins and rusty-coloured dead spots appear in the leaves.
• The tips of the leaves curl up radically and whole sections of the leaves begin to rot. The leaves keep on curling and ultimately fall off.
• An extreme shortage produces meagre, unhealthy-looking plants with strongly reduced flowering.

Reasons for a deficiency

• Too little, or the wrong type of fertilizer.
• Growing in potassium-fixed soils.
• An excess of sodium (kitchen salt) in the root environment, as sodium slows down potassium intake.

Solutions for a deficiency

• In case the EC in the substrate or soil is high, you can rinse with water.
• Add potassium yourself, either in inorganic form: Dissolve 5 – 10 grams of potassium nitrate in 10 litres of water. In acidic soils, you can add potassium bicarbonate or potassium hydroxide (5ml in 10 litres of water).
• Add potassium in organic form: Add a water solution of wood ash, chicken manure or slurry of manure (be careful not to burn the roots). Extracts of the grape family also contain a lot of potassium.

Extra Information

• In case the EC in the substrate or soil is high, you can rinse with water.
• Add potassium yourself, either in inorganic form: Dissolve 5 – 10 grams of potassium nitrate in 10 litres of water. In acidic soils, you can add potassium bicarbonate or potassium hydroxide (5ml in 10 litres of water).
• Add potassium in organic form: Add a water solution of wood ash, chicken manure ir slurry of manure (be careful not to burn the roots). Extracts of the grape family also contain a lot of potassium.

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Reproduced with kind permission from Canna-UK

What is Phosphorous?

Phosphorus plays an important role for all living organisms and is an essential nutrient element for plants and animals. It has a key position in the combustion processes of the cell, and in the total energy transfer of the plant. It is also a “building block” of the cell walls, the DNA, and all sorts of proteins and enzymes. For young plants, the presence of phosphate is indispensable; about 3/4 of the phosphorus consumed during a plant’s life cycle is absorbed in the first quarter of its life. The largest concentrations of phosphorus are found in the developing parts of the plant: the roots, the growth shoots and the vascular tissue.

Symptoms of a deficiency

Plants remains rather small with purple/black necrotic leaf parts, which later on become malformed and shrivelled.

Development of a deficiency

• At first, the plant becomes dark green – a different sort of dark green (blue/green) as appears when there is a shortage of potassium
• The growth in height, and the development of the plant’s side shoots are inhibited.
• After 2 to 3 weeks, dark purple/black necrotic spots appear on the old and medium-old leaves, making the leaves malformed.
• The purple/black necroses expand to the leaf’s stem. The leaf turns, curls considerably and dies off.
• The dead leaves are curled and shrivelled, have a typical ochre purple colour, and fall off.
• The plant flowers fully, but the yield will be minimal.

Reasons for deficiency

• Due to the low concentrations in which phosphate appears in nature, the affinity of plant cells for phosphorous allows easy absorption through the whole root. Therefore, shortages do not happen very often, except when:
• The growing medium has too high a pH (higher than pH 7). In such cases the plant cannot absorb phosphorus due to the fact that insoluble phosphorous compounds develop.
• The ground is too acidic, or too rich in iron and zinc. This hinders the absorption of phosphate.
• The soil has become fixated. Phosphate cannot be absorbed anymore.

Solutions to a deficiency

Always use inorganic phosphates as these are easy to absorb. Also always mix the phosphate fertilizer THOROUGHLY through the soil.
When pH is too high, acidify the medium by using a thinned solution of phosphoric acid.
Choose products that have a guaranteed phosphate percentage on the packaging instead of alternative phosphate-containing products like guano or manure.

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Reproduced with kind permission from Canna-UK

What is Nitrogen?

Nitrogen is one of the important elements a plant needs. It is an important part of proteins, chlorophyll, vitamins, hormones and DNA. Because it is a component of enzymes, nitrogen is involved in all enzyme reactions and plays an active role in the plant’s metabolism.
Nitrogen is mainly absorbed by the plant in the form of nitrate and ammonium. It can also be absorbed via small organic molecules. It is important that the balance between nitrate and ammonium is correct in the feeding otherwise the pH in the rhizosphere (environment immediately surrounding the roots) will become too high or too low. Plants with nitrate as their source of nitrogen have a higher organic acid content. This has an influence on the taste and storage life of the harvest among other things. Nitrate is converted into ammonium in the plant by the nitroreductase enzyme. Ammonium is then assimilated into organic molecules. Nitrogen has a positive influence on the plant’s growth. The plant gets bigger leaves, more branches and the vegetative period is extended.

Symptoms of a deficiency

• Stalks will turn purple and leaves will yellow and finally fall off.

Development of a deficiency

• The plant is a lighter colour as a whole.
• Larger leaves in the lower part of the plant turn light green. The leaf stalks of the smaller leaves now also turn purple. Typical vertical purple stripes appear in the stem.
• Leaves in the lower part of the plant turn more yellow and then become white. Finally, the leaves whither and fall off.
• The growth is visibly inhibited giving shorter plants, thinner stems, less leaf formation and smaller leaves.
• Further yellowing and whitening occurs in the top and middle parts of the plant.
• Leaves on growing points remain green longer but they are a lot less green than at normal nitrogen levels.
• Forced flowering starts and there is substantial leaf loss.
• Substantial reduction in yield.

Reasons for a deficiency

Deficiency can be caused by incorrect feeding or giving feeding that contains insufficient nutrient elements. Substrates that contain a lot of fresh organic material can cause nitrogen deficiency because microorganisms bind the nitrogen. A lot of nitrogen can be bound, particularly in the first weeks; this is released later but it is generally too late.

Solutions to a deficiency

Raise the EC of the feeding and rinse the substrate well with it.
Add nitrogen yourself to the feeding solution by using urea, blood meal, semi-liquid manure or by using a special “mono-nutrient’ product.
Spray the underside of the leaves with a nitrogen solution. This can best be done at the end of the day, just before the lights are turned off. Be careful not to cause burning.

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Reproduced with kind permission from Canna-UK

What is Iron?

Iron is a vital element for plant life. Iron has a number of important functions in the overall metabolism of the plant and is essential for the synthesis of chlorophyll. In general, iron is poorly absorbed by the plant. It can only be sufficiently taken up by the roots in certain forms and under proper conditions. Soil seldom contains too little iron, but it is possible that forms of iron that can be absorbed by the plant are lacking. The absorbency of iron is strongly dependent on the pH. Ordinarily, there is sufficient iron present in absorbable form in acidic soils.

Symptoms of a deficiency

Iron deficiency can occur during periods of heavy growth or high plant stress and is characterised by a strong yellowing of the young leaves and the growth shoots between the veins. This occurs chiefly because iron is not mobile in the plant. The young leaves can’t draw any iron from the older leaves. With a serious iron shortage, the older leaves and the smaller veins in the leaf can also turn yellow.

Development of a deficiency

• Green/yellow chlorosis, from inside to the outside in the younger leaves and in the growth shoots. The veins remain mostly green.
• Continued yellowing of the leaves to sometimes almost white. Also, large leaves turn yellow. This inhibits growth.
• In serious cases the leaves show necrosis, and the plant’s growth and flowering are inhibited.

Reasons for a deficiency

• The pH in the root environment is too high (pH> 6,5).
• The root environment contains a lot of zinc and/or manganese.
• The concentration of iron is too low in the root environment.
• The root temperature is low.
• The root medium is too wet, causing the oxygen supply in the roots to stagnate.
• The root system functions inefficiently due to damaged, infected or dead roots.
• There is too much light on the nutrition tank; light promotes the growth of algae. Algae also use up the iron and break down iron chelates.

Solutions for a deficiency

• Lower the pH.
• Iron chelates can be added to the substrate.
• Drainage can be improved, or the ground temperature can be increased.
• A leaf nutrient with iron chelates can possibly be applied. If a good fertiliser is used with hydroponic growing, an iron deficiency is almost out of the question.
• The best thing you can do is spray the plants with a watery solution of EDDHA – (max. 0.1 grams per litre) or EDTA chelates (max. 0.5 grams per litre).
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Reproduced with kind permission from Canna-UK

An aquarium plant, like any other needs nutrients in order to survive. In the natural world – rivers, streams, ponds, fields and hedgerows, plants will find the nutrients that they need in the soils and sediments. Soils and sediments are not uniform, some may lack certain nutrients and some may contain other nutrients in abundance. Some plants can survive quite happily with low levels of some nutrients and for others to do well they may require high nutrient levels. This is one reason why you might find lots of plants of a particular species in one area and none in another

An aquarium however is not a natural world but a very artificial one! It is also finely balanced and has to be carefully managed in order to maintain conditions, which, as far as the fish and plants are concerned is as near natural as possible.
Water temperature, oxygen levels, pH and water hardness must all be controlled and just as fish need to have to have food, plants have to be given the correct nutrients in correct quantities.

In both agriculture and horticulture fertilisers can be provided from manure and composts. These are not options in the planted aquarium so chemical fertilisers are used. The main advantages of chemical fertilisers are that you know exactly what is being put into the aquarium and in what quantity.

Regular water changes are important in any aquarium to prevent the build up of toxins and as long as chemical fertilisers are used in conjunction with a regular water change routine, you will be able to control the conditions in the aquarium and maintain that fine balance.

The chemicals mainly used in planted aquariums are:-

Potassium nitrate – to provide nitrogen and some potassium
Monopotassium phosphate – to provide phosphorous
Potassium sulphate – to provide extra potassium
Magnesium sulphate – to provide magnesium

These provide the main macro-nutrients – nutrients required in relatively large amounts.

In addition to the macro-nutrients micro-nutrients are required – these are required in relatively small amounts. These can be sourced from separate chelates but as they are needed in such small amounts it is easier to use a ready made “trace mix.”

The information on the back of a bottle or packet of fertiliser can be difficult to understand. It may list the ingredients and  appear to give the % of each element, however things are not as simple as they may appear.

The three main elements in most fertilisers are nitrogen (N), Phosphorous (P) and Potassium (K). You may see three numbers prominently displayed on some fertilisers – 4 1 3 for example. This is the ‘NPK’ ratio and means (in theory) that it contains 4% nitrogen, 1% phosphorous, and 3% potassium.
However on the list of ingredients although you may find nitrogen (or N) you may not find ‘P’ or ‘K’. Instead you might see P2O5 and K2O (phosphorous pentoxide and potassium oxide) even though the fertiliser does not actually contain either of them!

It is done this way in order to comply with UK fertiliser laws.
The reasons are historical. In the 19th century and without the aid of the analytical instrumentation available today, the phosphorous and potassium content could not be measured directly. Instead the fertiliser was burnt and the residual ash, phosphorous pentoxide or potassium oxide, was measured instead.

There is another source of confusion to those of us who are not chemists! Many articles written about fertilisers refer to nitrate (NO3) and phosphate (PO4) rather than to the elements themselves. This is understandable because it is usually a nitrate that is providing the nitrogen and a phosphate that is providing the phosphorous. The good news is that it is easy to calculate the actual quantity of the individual elements and vice versa:-

If something contains 12% P2O5 it will contain 12 x 0.436 = 5.23% phosphorous

Other symbols and abbreviations often used in connection with fertilisers are %, ppm, W/V and V/V

% (per cent) is the same as parts per hundred. Potassium sulphate contains 44.9% potassium. This means that 100 grams of potassium sulphate contains 44.9 grams of potassium.
ppm is an abbreviation for parts per million. Some of the nutrients required by plants are needed in such small quantities that using % as a measure would have too many zero’s. 1 ppm = 0.0001%

Sometimes, after a % or ppm value ‘W/W’, ‘W/V’ or ‘V/V’ might appear. W stands for weight and V for volume. ‘W/W’ Means that the % or ppm has been calculated on a weight for weight basis.
In the example above 44.9% is actually 44.9% W/W i.e. weight per weight.

It is usual to measure solids (powders) by weight e.g. grams (g) or kilograms (kg) and liquids in litres (l) or mille-litres (ml).
When a solid is dissolved in water however it is often easier to calculate the % of an element or the ppm as W/V (Weight per Volume)