[Weekendhippie]

My few cents. I’m not an experienced grower but an educated chemist. I have hard water too, harder than yours approx 750-800 ppm according to sparse analysises from the water supply. It has caused me pH issues, pH being too high and fluctuating, sometimes above 8 from the tap. An I was naive to think that I could grow without pH adjusting, so I didnt buy a pH pen before I ran into trouble. Nutrient lockout.

My current solution is to dilute the tap water with condensed water from the dehumidifier and pH adjusting it – tested and works (40-50% “dehumidifier water” and 50-60% tap water). If you don’t have some water with basically no EC thats not an option. I could just save the water from the dehumidifier for that use.

In the future I think I’ll just use nitiric acid to pH adjust. The main components of hard water is CaCO3 and MgCO3. If you add HNO3 to perhaps pH =6.0-6.1 you will see the water starting to bubble. It is CO2 that bubbles off. Now you have converted some of the CaCo3 and MgCo3 to CaNo3 and MgNo3. Your water is now at a point where you can say that is very similar to some water that have been added some Cal/Mag. The nitrogen can be used by the plant. I’ll watch out for not giving the plant too much N.

The benefit of keeping some Calcium Carbonate (CaCO3) in there is that it buffers the feed water and soil at around pH that is in the preferred range. pKa is 6.35. For those who does not know what pKa is, the breaf explanation is that this is the point where it takes the most acid to move pH down and an equal amount of OH- to move pH up. You can make a kitchen sink experiment that will visualise what I’m talking about. Grab some hard water 4l’ish that typically comes with a high pH 7-7.5 ish. A pH pen. And some acid (acedic acid (vinegar), pH down (some acid), Citric acid solution or any other properly diluted acid)). Measure the pH. Start adding a small amount of acid to the water and measure the pH. Note the amount of acid added and the pH. Keep going until you hit at least pH 5.5. Now plot the pH vs amount of acid added. You will notice a S-shaped curve where it takes a lot of acid to move the pH around the pKa value. If you dont find it around 6.35 you should calibrate you pH pen because it is off.

In my tap water the Mg is a little low compared to Ca. If it give Mg deficiencies that can be solved by just adding a little Epson salt – best solution. Or some Cal/Mag.

If you want to use a water softener you should not use Sodium Cloride, find som Potassium Cloride instead. Sodium will just add to the osmotic pressure or give you a base EC from something the plant can not use. Potassium can be used by the plant. It is the K in main nutriants (NPK). Harley Smith spoke about that in a podcast I watched.

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