If you don’t know about Background Conductivity, you better grow in soil

When we are about to set our first hydroponic system, one of the first things that come to our minds is how much and where to find the stuff to grow the first big, huge, and overloaded fruits and flowers. Then, you start looking for a place to grow them, some containers, hydroponics pumps, light systems, growing media, and much more. However, as soon as you have all set, a new problem comes to light making your life miserable and your plants as good as a zombie.

Yes! We are talking about water and that is important!


In hydroponics there are two significant concepts that every grower have to understand in order to avoid unpleasant moments when growing their plants, and these are Background Conductivity and Hard-Soft waters.

Let’s get started with Background Conductivity:

  • First: The water with a lower concentration of salt and other mineral contaminants is called pure water.
  • Second: Conductivity is a measure of how well a solution conducts electricity. To carry a current a solution must contain charged particles, or ions. Most conductivity measurements are made in aqueous solutions, and the ions responsible for the conductivity come from electrolytes dissolved in the water. Salts (like sodium chloride and magnesium sulfate), acids (like hydrochloric acid and acetic acid), and bases (like sodium hydroxide and ammonia) are all electrolytes.
  • Third: Background Conductivity is the measure of the conductivity of the water before any hydroponic nutrient is added.

In few and simple words, Background conductivity measure the amounts of salts, acids, and bases accumulated in a solution when the water is absorbed or evaporated, and if this measure is too high, your plants are going to be exposed to a very serious risk of contamination, dryness, and possibly death.

For example: The common elements found in the water are Ca & Mg. So, If your water has a high concentration of Calcium (Ca) and Magnesium (Mg) and you decide to add a hydroponic base nutrient or any other additive rich in those elements, guess what! You are going to overload your plants and burn the hell out of them.

The answer can be found in the rain or any other source of desalinated water (R.O water). The use of low background conductivity water is the best way to avoid serious risk in hydroponic cultivation. Many people use tap water in their reservoir and it’s ok as soon as you know the amount of salt and other elements contained in the system. If the water has a background conductivity below 150 ppm you will be fine. However, the maximum acceptable B.C can be around of 350ppm; keep that in mind before you start to grow hydroponics.

Hard Water and Soft Water


          "As I mentioned above, Ca & Mg are the most common elements found in water so keep that in mind."


Now, Hard water is generally considered to be water that contains more than 60 ppm dissolved calcium and magnesium. The problem with hard water is that it also contains many other different types of contaminants in amounts which vary greatly depending on the water source and its geographic location.

The variation is so critical that even within a single city you may find large variations because as we know, cities often have more than one water source. This is one of the reasons that there is no hydroponic nutrient that can compensate for hard water in all areas and that is a fact. Remember, and Yes! I will say this one thousand times, if there is too much of these elements (Ca&Mg), the nutrient solution will be out of balance which can lead to serious deficiencies.

Hard water usually has a high pH (a measure of hydrogen ion concentration; a measure of the acidity or alkalinity of a solution. Aqueous solutions at 25°C with apHless than seven are acidic, while those with a pH greater than seven are basic or alkaline.) and a heavy load of bicarbonates that cause another problem.

For example, in the run to waste, some very hard water may require an input pH 4.0 and may run off at pH 8.0 giving an average of Ph 6.0. At these levels you are going to require a lot of acid. In addition, your hydroponic nutrient solution may become unbalanced because of the amount and type of acid used. The best way to solve this problem is to get better water where possible.

See? That’s why this is so important!


Soft water:

                     "Ca & Mg are one of  the most important elements used by plants for its own development."


This water does not contain significant amounts of Calcium (Ca) and Magnesium (Mg). Soft water is definitely easier to use in your grow room than hard water because as you can see, salt levels are not too high. For this reason, the main advantage of using soft water is that it is easier for managing Ph.

We hope this post had been useful for you, we are working hard to bring you the best and most important topics in this amazing and humble industry called hydroponics.

Conductivity Conversion Table.


These are the Conductivity levels you should maintain:

Remember that some of these values depend on the how, where, and what are you using in your hydroponic system.

Vegetative: E.C  1.6 - 2.2  

                   C.F   16 - 21

                    ppm 1145 - 1600

Flowering:  E.C  1.8 - 2.4

                   C.F   18 - 24

                   ppm 1250 - 1750 



Older Post
Newer Post
Close (esc)


Use this popup to embed a mailing list sign up form. Alternatively use it as a simple call to action with a link to a product or a page.

Age verification

By clicking enter you are verifying that you are old enough to consume alcohol.


Shopping Cart

Your cart is currently empty.
Shop now