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Hard Water In Hydroponics

What is Hard water?

Hard water has high levels of alkaline minerals, principally Calcium and high levels of carbonate and bicarbonate ions.  There are HW areas all over the US from Northern Michigan to New Mexico.

You can usually tell if your water is Hard as you will tend to get deposits of “lime scale” on faucets and sinks.  You may also find that soap fails to lather well.


How can I tell if my water is Hard?

Ask your hydro retailer for a Total Alkalinity Test Kit.  It is a cheap and simple test and is accurate enough for the purpose.  If the test shows anything close to 150 ppm or higher then you can consider your water is Hard.


Why is it so important?

Hard water has ruined many a hydroponic project.  Also many growers have struggled for years with reduced plant performance and lower yields and have never known the reason for it.

HW already has many of the minerals needed for plant growth.  When you add a normal nutrient solution you are just adding an excess of key elements.  This quickly leads to an imbalance in the tank.

HW will buffer the pH of the solution.  The bicarbonate ions have to be neutralized before the pH will come down.  If you use a “normal” nutrient with HW you will find that you need to add a lot of pH Down afterwards to get the pH into the right area.  The problem with this is that using Phosphoric acid to lower the pH involves adding large amounts of phosphate ions to the nutrient.  This causes an immediate imbalance and can lead to very serious problems in a short time.


What can I do about it?

The easy answer is to use a nutrient solution formulated especially for Hard water.  A proper HW solution is formulated to take account of the mineral ions present in HW.  It is also much more acidic than a normal solution.  For most people this means they will not have to add pH Down or if they do the amounts needed will be a tiny percentage of what they were before.  A HW solution will mix with your water to make up a perfectly balanced nutrient profile that will remain in balance for the maximum possible time.


This means better growth, healthier plants, and higher yields.

IONIC Nutrients are available in a normal formulation and a Hard water (HW) option.  IONIC Nutrients can be found at your local hydro store.  They represent the pinnacle of hydroponic nutrition for Hard or soft water.  If you have a problem finding IONIC please contact Hydrodynamics International and we will put you in touch with your nearest supplier.