WHAT IS WATER-HARDNESS AND WHY DOES IT MATTER?
What is hard water? Water-hardness refers to the alkaline mineral ion count, usually from Calcium Carbonate and bicarbonate. Water with a high count is called Hard Water. You can usually tell if you are in one of the many areas of Europe where hard water is present because your kettle will get a build up of ‘Lime scale’ on the inside.
Water-hardness can be measured in parts per million by using a total alkalinity test kit. These cheap simple test kits are available from your local hydroponics retailer and are quite accurate enough for the purpose. If your water-hardness tests at anything over 150ppm it should be considered to be hard. Do not be alarmed if your water is hard, it does not mean you cannot grow things using hydroponic methods.
Why Does My Water-Hardness Matter?For many years growers in some areas have had unacceptable results, with low yields and poor plant performance. The reasons for this have been unclear until it was realised that the plants were suffering from a chemical imbalance. Hydroponics growers were particularly badly affected in these areas.
Growing hydroponically using normal nutrients means adding a balanced solution of chemicals to the hard water. The hard water already contains an excess of some of the essential minerals that the plant needs and so the solution quickly becomes imbalanced in the nutrient tank.
In order to reduce the pH of the standard nutrient solution the bicarbonate ions have to be neutralised. Because these alkaline ions buffer the solution it is necessary to add large amounts of Phosphoric acid to the nutrient in order to reduce the pH. This in turn increases the Phosphate ion content of the solution causing an imbalance. This imbalance can have serious consequences for your plants in a very short period of time.
What can I do about it?The simplest way around the problem is to use a nutrient formulated specifically for hard water areas. A Hard Water nutrient has been produced with the correct balance of nutrients to compensate for the excess alkaline mineral ions in the water. These nutrients are also much more acidic to combat the buffering action of the bicarbonates.
The benefit of using this formulation is that you will not have to add large amounts of adjusting chemicals to your nutrient in order to achieve the correct pH. Also your plants will have a balanced nutrient solution containing all the ingredients they require to thrive. This means that your crop will grow up healthy with better growth and a superior yield.
For more information about water-hardness testing equipment