Top 10 Common Hydroponic Terms You Should Know

Common Hydroponic Terms

Are you someone who has recently started learning and exploring hydroponics? Do want to build a perfect hydro garden inside your house or on your terrace? If yes, then you should know these common hydroponic terms used in the hydroponics market. These terms are very commonly used among hydroponic communities on the internet and if you don’t know any of them then you might just feel lost in the bush. 

So, I have collected a few terms which I think are absolutely necessary if you want to succeed in hydroponics as these basic terms will define the knowledge you have and will surely increase the level of confidence and judgment you can take while setting up your own hydro system. 

NOTE: This in any way is not an exhaustive list of terms. You will not be learning everything here. These are just the basics. If you know these then you can advance to the next level. 

So here is an overview of the common hydroponic terms that we will be covering in this article.

So Let’s Begin 

Controlled Environment Agriculture (CEA)

You may often encounter this term while researching hydroponic systems. Controlled Environmental Agriculture is not exactly Hydroponics. Hydroponics is a type of controlled Environment Agriculture. CEA is basically a technology-driven approach to farming. As you might be knowing that everything is provided in a measured quantity to hydroponic plants, be it light, water, or nutrients. Hence we tend to build an artificial atmosphere for the crops in which they can grow better than in soil. 

CEA is focused on optimizing the resources and increasing the yield of the crop. Other types of CEA which are used in both commercial and non-commercial farming are aeroponics, aquaculture, and aquaponics. 

Dissolved Oxygen (DO)

Like any other living thing in this world, hydroponics also requires oxygen. But as I stated earlier everything in a hydroponic system is measured and supplied accordingly. So, oxygen makes a very important part of growing a plant and as hydro plants are always dipped in a liquid to get nutrients we need to check whether the oxygen in that nutrient solution is appropriate for the plant or not. This is what DO indicates. It is a measure of the amount of dissolved oxygen in the nutrient solution, basically how concentrated the nutrient solution is with oxygen.   

Electrical Conductivity (EC)

If you have ever tried to make your own nutrient solution at home then you must have encountered this term. This term is closely related to the strength of a nutrient solution. I have studied chemistry as an undergraduate so I can tell you a bit more about this one. 

See, plants absorb nutrients via roots. The root can only absorb those nutrient elements which are in free form i.e are ions for example OH–   or H+ ions. These can be picked by the plants easily. What these ions do is increase the electrical conductivity of the solution. These ions act as a medium for electricity to flow.

Also Read “How to fix Root Rot in Hydroponics

So, when we measure electrical conductivity and if we see that electricity is being conducted nicely that means the concentration of free ions or the strength of the nutrient solution is high. This is denoted by EC. 

High Intensity Discharge (HID)

This is a type of grow light. Grow lights help you to increase yield and keep the plants healthy especially if the weather outside is not favourable to the plants you are growing.  An HID light is just like a gas lamp but a modern lamp. The chamber is filled with inert gas and the electrical conductors run electricity across the gas, the gas emits light of high intensity.

They are losing popularity as LED grow lights are gaining market mainly due to their high maintenance cost and they are bulkier as well. An HID light needs a reflector, a ballast, and a timer separately to be fully functional for a hydroponic system. 

High Intensity Discharge Light - How Hydroponics

Cool White Fluorescent (CWF)

This is also a type of grow light having a spectrum range of blue light. It is a supplemental light for the plants in the seed or bloom stage. As per the American Standards, the colour temperature for CWF stands at 4150K, although most of the light available for hydroponics have a temperature rating of more than 6000K.

Photosynthetically Active Radiation (PAR)

This is the most important parameter when it comes to checking the efficiency of a grow light. Mostly in the case of LED grow light PAR efficiency ranges from  2.5 – 3.15 umol/J. In general terms, it is the amount of light spectrum that is available to the plant for the process of photosynthesis. So, a thumb rule for choosing a grow light is that the higher the PAR value better will be the growth. 

Photosynthetic Photon Flux (PPF)

Again a very important parameter while judging grow lights. PPF is used to measure the amount of light produced per second in the PAR range. Basically, it is the number of photos (Light packets) travelling towards a surface per second. This gives you an idea of how much light you will be needing for your hydroponic setup. 

For example, if you want to set up a spinach garden that requires a light flux of 100 umol per meter square. And if you have spread your spinach garden into 5 systems of 20-meter square area each then the total area becomes 100 meters square. 

Now the total PPF required is 100 x 100 = 10,000 umol. 

So in case you decide to go with a Mars Hydro SP 6000, which has a light output of roughly 1350 umol/s, then you will be requiring almost 8 light to cover your whole garden. 

Photosynthetic Photon Flux Density (PPFD)

PPFD describes the actual quantity or density of light hitting the plant area in the 400 to 700 nm range i.e. the photosynthetically active light.  PPFD is measured in umol/s.m2  that is the number of light packets/photons hitting an area of 1 meter square per second. If you are looking for power grow light then consider checking the PPFD, the higher the better. 

Daily Light Integral (DLI)

DLI is also used to gauge the performance of a grow light. It is the amount of light received by a specific area of the plant, for example, the centre of the leaf, in a 24 hour period. The light that is measured should be emitting photosynthetically active photos i.e light in the range of 400-700nm. Grow lights have their spectrum in this range only except a few of them also have Infrared blasters.  

Common units used in Hydroponics

Nanometer (nm)

A nanometer is used to measure microscopic things. One nanometer is equal to one billionth of a meter. If you want to convert nanometer into meters then you have to multiply it by 10-9 and if you want to convert it to centimetre then multiply it by 10-7.


This is used to quantify the number of photons produced by a grow light while measuring its PAR efficiency and PPF. One mole equals 6.02 x 1023 items. Because mol is such a big number you will always see it as umol which is a micromol. 

A umol = 6.02 X 1017 items

PPF is measure in umol/s 

And PPFD is measure in umol/s2


This is a commonly used term used to describe the number of elements or impurities present in water. PPM or parts per million is used to describe the concentration of the solution. Mostly electrical conductivity is denoted by PPM in the case of hydroponics. In households, we use PPM to measure the quality of our drinking water. Hard water has a higher PPM than soft water.