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Should You Give Your Marijuana Plants Hard Or Soft Water?


First, inspect the water for any dissolved solids. An adequate amount should be between 100 and 150 parts per million (ppm). Water that is low in dissolved solids (soft water) should be readjusted up to 150 ppm using Cal-Mag solution. Water that is too high (over 250 ppm of dissolved solids), should be filtered with ionic or reverse osmosis filters.

Hard water restricts a balanced nutrient uptake. You can mix filtered and unfiltered water to create a water mixture that’s suitable for plants. A test of the water supply in a Los Angeles suburb measured at 450 ppm of dissolved solids. After using an ionic filter, the water had a ppm of 13. The gardener, then mixed one part unfiltered water and two parts filtered water which yielded about 150 ppm. Hard water deposits can be detrimental to hydroponic/aeroponic systems. Download my free marijuana grow bible and learn more about watering marijuana.

Sodium in water

Try to stay away from any water with high concentrations of sodium. The plant will absorb sodium prior to any other element, which causes the plant’s vascular system to deteriorate. Also, any water that’s been treated with water softeners should be avoided.

Sulfur in water

Any water that has a sulfurous odor should have its pH checked. Sulfur is highly acidic and the water might have a relatively low pH. You can adjust the pH of the water with pH Up. Soil that’s been affected by the water might also have a low pH. If necessary, lime can be used to raise the pH in the soil.

Chlorine in water

The irrigation water has substantial amounts of chlorine. Does this have a negative effect on the plants?

Solution: Chlorine can affect plants in many different ways. Firstly, it can kill some microorganisms that form a community with the roots in the rhizosphere of some media systems. This phenomenon can result in slower growth. Chlorine can also be the cause of some leaf tip burn, usually on hot, sunny days when the plant requires a lot of water.

Most gardeners still use water straight from the tap that has likely been treated with chlorine and maybe fluoride depending on your municipality. Despite the presence of these chemicals, plants thrive, even though they might grow better with non-chlorinated water. Most cities chlorinate their water supply with chloramines, which can’t be eradicated through boiling or simply allowing the water to stand. If you really want to get the chlorine out of your tap water, you can use activated carbon filters. Specialized UV systems are designed uniquely with dechlorination in mind. There are several chemical dechlorinators on the market for use in fish ponds and aquariums. These products are innocuous to fish and plants, but the author hasn’t used them and cannot say with any degree of certainty which product works best for marijuana gardens.

If you want to start growing, download my free grow guide and order some marijuana seeds. All top quality marijuana seeds are available in my marijuana seed shop. We ship seeds to the US, CA and many other countries. For any growing related question please visit the marijuana support page.

Source: ILoveGrowingMarijuana.Com



About Author

Robert Bergman is a master marijuana grower. Robert Bergman is the author of 'Marijuana Plant Care' and 'The Marijuana Grow Bible'.


  1. Yes! Being a organic and vegan grow, we managed to use a few drops of lime juice (from those dumb plastic lemons/limes lol) per gallon. Just took a little testing to get right, the good news is that the plastic lemons/limes have kinda built in droppers. All natural and ultra cheap! Not sure I recommend this idea, but it works well if anyone is doing chem-free organic and when dialed in just right :) Yeah it’s just citric acid, but we felt more natural this way lol.

  2. Humboldt Star on

    Try citric acid to lower the ph, its available through atlantis hydroponics and its all natural, it only takes a very small amount to lower the ph, use carefully

  3. Yup, that’s exactly right. The Florida aquifer (which is under FL and southern parts of GA, SC, and AL) has been fed by a few hundred thousand years of filtering through rock, mostly limestone and it’s relatives. 8.3 still caught me by surprise though lol, that’s 100 times more alk than the beloved 6.3 heh.

  4. Humboldt Star on

    I have grown many excellent crops with soft mountain water, cal mag was not needed at all.

  5. At one patient site, we had some very strange and sudden issues, and finally tracked it down to the water source. We assumed that the water was perfect, as it is a 200 foot drilled well, all the way down to the Florida aquifer! All natural, not city or “tap” water, and yet it registered a whopping 8.3 ph yikes! The ppms were numerically ok, but I could tell it was high in sulfur (smell), and way high in calcium (calcification on showers and faucets). A week of trying bottled distilled water and they’re fine. So, don’t ever assume your water is perfect hah!

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