Monitoring Equipment

There are many options for monitoring your homemade hydroponic system. I have put these in order of importance for your system.  Please note that for optimal produce and commercial systems all of these are important.

CF MeterCF Meter

The concentration of nutrients in a solution is measured as Conductivity Factor (CF),  the more nutrients in a solution, the more conductive the solution becomes. The CF level of your hydroponic solution is the most important to control; it is actually possible to starve your plants by having too higher nutrient concentration, this process is called reverse osmosis (some weed killers use this method)

CF Meters range hugely in price, models can be found from around $100 for a hand held model to many thousands of dollars for fully automated CF control systems.

CF Meters can be purchased from Amazon, click here for the CF meter I use Blue Lab Commercial Truncheon PPM / EC / CF Meter

Litmus Paper / pH Meter

The acidity / alkalinity of your nutrient solution is measured as pH.  Pure water has a pH of around 7,  acidic solutions have a pH below 7 and alkaline have a pH above 7.

The pH level of your nutient solution is the second most important.  Different minerals in the solution are released at different acidity levels, there is a chart showing the absorption levels here .  A pH range between 5.8 and 6.3 is good for most plants.

Litmus Paper is a very cheap way of checking the pH level of a solution.  A paper strip is dipped into the hydroponic solution and it will change color.  Litmus Paper comes with a color chart, the strip is compared to the color chart, this will show the pH of the solution.

A pH Meter performs the same task as Litmus paper, the meters do cost a lot more than Litmus Paper.  Most pH meters have a sensor probe and digital display.  The sensor is placed into the hydroponic solution for a specified time and the pH level will be displayed on the meter.  The sesor probe on pH Meters normally need to be re-calibrated regularly, a calibration solution is provided with most sensors, this solution is at a know pH level allowing you to calibrate the meter.


Combo Meter

Combination Meters

Combination meters are available and generally work out much more cost efficient than purchasing the meters individually.  The displayed model is available on Amazon, click here to go directly to the Amazon page Bluelab Combo Meter pH, Conductivity and Temperature Monitor

CO2 System

Plants breath carbon dioxide (CO2) and need for photosynthesis.  CO2 is present in relatively low quantities, 300-450 Parts Per Million (ppm) in the air. Plant growth can be increased and accelerated by as much as 35% if the level of CO2 is increased to 1500 ppm.

There are several basic CO2 systems that you can easily build or buy

CO2 Fish Tank SystemFermentation

The CO2 systems used in fish tanks can be used.  Place the CO2 dispersion unit into a container of water.  These units can be purchased from Amazon, click this link to be taken directly to the page on Amazon Hagen Nutrafin CO2 Natural Plant System with CO2 Activator and Stabilizer

Using a plastic soda bottle, a soft plastic tube and a small container.  Drill a hole in the lid of the soda bottle and carefully glue the tubing into it, making sure the hole is completely sealed.  Glue the other end of the piping into the bottom of the container.  Put several inches of water into the container, ensure that the end of the pipe is fully submerged.  Put a cup full of sugar and two teaspoons of yeast into the soda bottle and fill to around 1/2 way with warm water.  As the mixture ferments, CO2 will be produced and slowly released through the water.

Oil Lamp / Candle

The most simple CO2 is an oil lamp or candle (tea lites are good and burn for a long time), as these burn, CO2 is released.  Please remember that fire can be dangerous, ensure that you have these well away from anything flammable.


CO2 Bottle SystemCO2 Bottle

For larger scale glasshouses CO2 can also be purchased in gas tanks and be released into the growing environment using regulators and solenoid valves.

Small CO2 gas bottle systems used in fish tanks can also be purchased from Amazon, these are good in a small enclosure.  Click here to go directly to the page on Amazon Fluval Mini Pressurized 20g-CO2 Kit – 0.7 ounces



A thermostat is used to regulate the temperature of your glasshouse, they can be used to automatically open and shut windows, run fans and control heaters.






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Nutrient Acidity – pH

pH is the measure of Acidity and Alkalinity of a solution.   pH is measured on a scale of 1-14 with 7 being neutral, Acids have a pH lower than 7 and Alkalines have a pH higher than 7.

The level of acidity in your homemade hydroponic system is very important.  Each of the essential elements making up the hydroponic nutrient are released into the nutrient solution at a specific pH range.

Plants are only able to absorb nutrients that have been released into the nutrient solution.

Nutrient pH Range

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The optimal pH range of hydroponic nutrient solution is 5.8-6.3

If the pH goes below 5.5 then the concentration levels of available micro-nutrients Iron, Manganese, Boron, Copper and Zinc will increase and can become toxic to the plant.  The increase in micro-nutrients will also decrease the availability of Calcium and Magnesium.

The affect of the change is nutrients is much more important in hydroponics as this is a closed system with no soil to buffer the nutrients.

Measuring pH

There are several ways of testing the pH of your nutrient solution.  These are listed from cheapest to most expensive.

Litmus PaperLitmus Paper

Litmus Paper are strips of paper that have been impregnated with a pH sensitive dye.  The dye changes colour when dipped into the nutrient solution.  The paper is then compared to a colour chart to determine the pH level of the solution being checked. Litmus paper comes in pH ranges, so ensure that you purchase one the will cover pH 5 to pH 8.

Liquid pH Test Kits

Liquid pH Test Kits work by adding a few drops of a pH sensitive dye to a small amount of the nutrient solution and then comparing the color of the resulting liquid with a color chart.

pH MeterpH Meter

pH Meters are an electrical monitor device that will display the pH level of your nutrient solution in seconds.  There are a huge range of pH Meters, ranging from inexpensive pen-like devices to expensive commercial models.

Please Note

pH Meters need to be looked after properly and calibrated regularly.  Most pH Meters need to have the actual sensor to be moist at all times and to be stored in a buffer solution.

pH Buffer SolutionAdjusting pH

pH Buffer solutions are available at your local hydroponic store.  These solutions will raise or lower the pH of your nutrient solution to the desired level.

With small a small nutrient reservoir the amount of buffer solution will be minimal, so take care or you could over buffer your nutrient solution.

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Essential Nutrients

Hydroponic MineralsThere are 12 main elements required for successful growth and propagation of a plant.  Here is a brief description of the elements and their main purposes.  A good hydroponic nutrient solution will have all of these combined in the correct proportions to promote plant growth


Nitrogen is one of the main elements contributing to the growth of a plant.  Plants convert nitrogen to produce amino acids and proteins which are used to produce new cell growth.  Any deficiency of nitrogen will result in the new growth being weak and spindly.  Shortage of nitrogen is usually visible when a plant loses it’s green colour and becomes yellow, this is because nitrogen is required for producing the green pigment chlorophyll in the leaves.


Phosphorus is another important element for plant growth and is vital for photosynthesis and cell formation.  Phosphorus makes it easier for the plant to transfer energy, production of a good root system, and formation of the plants flowers and seeds.  A deficiency of phosphorus will result in the leaves of the plant becoming a deep green colour.


Potassium much like phosphorus acts as a catalyst within the plant to activate a number of plant functions.  Potassium is important to ward off disease and plays an important role in call growth.  A deficiency in potassium can be seen by the mottling of older leaves and a yellowing of the plants veins.  Plants low in potassium are likely to lose their fruit before it ripens.


Calcium is the element that support the cell walls in plants as they form.  Calcium helps to buffer the excesses of  other elements and is an important part of the plants root structure.  Calcium tends to be in greater concentrations in the older parts of a plant, this is because it is not very mobile.  Any deficiency of calcium is visible on the new growth of the plant, the new leaf tips and growing tips tend to die back and leaves show a brown to blank scorching.


Magnesium is another important element used in photosynthesis.  It is vital to the chlorophyll and is used extensively in the production of seeds.  A deficiency in magnesium will cause a yellowing on the plants leaves spreading from the centre of the leaf to the edges, seeds produced are also of inferior quality and may be deformed.


Sulphur is as important to the plants structure as calcium.  Sulphur is one of the components that play an important part in producing the flavours and odours in most plants.  A deficiency of sulphur shows on the younger leaves, they become very pale.  A plant will continue growing with a sulphur deficiency only it will tend to be very woody and the plant will grow slowly


Iron is necessary for the production of chlorophyll in plants and is used in photosynthesis.  A deficiency of iron will result is the plants new growth becoming almost white and the veins yellowing.


Manganese is involved with many enzymes in plants, especially those that reduce nitrates before proteins are produced.  A deficiency of manganese will result in mottled yellowing of the younger leaves, the formation of blooms is also adversely affected.


Zinc is an element involved in the growth of hormones and is important for most plant enzymes.  Zinc increases the source of energy for the production of chlorophyll and promotes the absorption of water.  A deficiency of zinc will result in extremely undersized leaves.


Copper is used by plants to activate several important enzymes.   Copper increases the sugar content in citrus and intensifies the colour of plants like carrots and apples.  A deficiency of copper will result in the wilting of new growth, shoots dying back and fruit splitting before it is ripe.


Boron is an element necessary for the normal cell division, protein formation, pollination and seed production  in plants.  A deficiency of boron will result in the death of the plant starting with the main growing points.


Molybdenum is used in the formation of proteins by plans and affects the ability of the plant to obtain nitrogen from the air.  A deficiency of molybdenum is indicated by pale leaves with burnt looking edges, the leaves may also become distorted.

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Hydroponic Nutrient Basics

A lot of mystique appears to have been unnecessarily created around hydroponic nutrition.  Hydroponic plant nutrition is no different in terms of requirements than conventional plant nutrition.

Nutrient Formulations

It is possible to make your own hydroponic nutrients, this can be advantageous for specialised commercial growers, for home use store purchased pre-mix is ideal.

Pre-mix formulas come either as powder or liquid and generally will be supplied in two parts  that you will need to mix in equal quantities for use in your hydroponic system.  Do not be tempted to pre-mix to the two parts before they are required to be used, the two parts can react together and you can end up with a in-dis-solvable sediment in the bottom of your container.

As with most plant foods, hydroponic nutrients consist largely of Nitrogen (N), Phosphorus (P) and Potassium (K).  A selection of other elements including Sulphur, Calcium, Magnesium, Sodium, Iron, Manganese, Zinc, Copper, Boron will also be added to the nutrient to provide balanced nutrition for the plants.

There is a large range of hydroponic nutrients ranging from specialising in flower blooms, specific plants through to general formulations.  I recommend using a general formulation

Nutrient Absorption

The process by which mineral nutrients dissolved in water are absorbed into plants is called osmosis.  Osmosis is the tendency of fluids to pass through a semi permeable membrane and mix with one another.  In plants the small hairs on the roots allow nutrients dissolved in water to enter the root system and do not allow particles of dirt for example to enter.

The cells in the plant’s root hairs contain a dense solution of salts and organic acid.  Because this solution is stronger than the weak solution of nutrients dissolved in the water surrounding the roots, there is a strong osmotic pressure driving the weak solution in through the cell walls to mix with the dense solution in the plant root hairs.


Osmosis can also work in reverse and kill a plant.  If the concentration of nutrients in the solution surrounding the plants roots is stronger than the concentration of nutrients in the plant’s root hairs, nutrients will move from the plant into the solution in effect starving the plant.

The concentration of nutrients in a solution is measured as Conductivity Factor (CF).  The more nutrients in a solution, the more conductive the solution becomes.

The acidity / alkalinity of a solutions is measured as pH .  The pH of the solution affects the plants ability to absorb the nutrients.

I will cover the importance of CF and pH in a future post.

Monitoring the Nutrients

CF Meter

For Static Solution Culture or Run to Waste hydroponic systems you can mix the nutrient solution to the required CF by measuring the required quantities following the details on the hydroponic solution you have purchased, for other hydroponic systems it is better to measure the CF using a CF meter

There are a large range of CF meters available.  Ensure you purchase one that has a CF range from 2 to 36 as this will cater for most plants that you are likely to grow

The easiest way to check the pH of the solution is to purchase some litmus paper, this simple is dipped into the nutrient solution and will change colour to display the pH of the solution

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