For a general assessment of your water quality test the pH and EC range with your essential kit. Also look at the colour of the water and if it has any strong smell. If you notice anything out of the ordinary you can give a 1L sample to the pharmacy for a chemical analysis. The pharmacy sells sterile bottles for this purpose. The analysis usually costs 50-60$/Euro and provides details of common harmful contaminants. This is especially recommended for testing well water. It helps to say that you need an analysis for drinking use and watering plants so that specific contaminants are tested for. If you need to install an osmosis filter for heavily polluted water you will need this analysis to purchase the correct osmosis system and filters.
*Vinegar is a neutral acid that is completely harmless to plants when diluted in water. It should be used to adjust the pH of the water for soil cultivation to prevent overfertilizing of plants. The commercial pH DOWN products all contain potent nitric or phosphoric acid that raise the salt level in soil and can burn your plants. Especially seedlings and young plants easily suffer from regular watering with pH Down.
Tap water and well water are two main sources that need to be checked for quality. Both can be contaminated with toxic levels of minerals. High levels of sodium (Na) are often found in well water and can cause excessive damage to plants. Saline water on the whole must be avoided.
Usually a household osmosis filter is sufficient to clean water from common impurities such as calcium, magnesium, and low levels of salts. The cost of 100,-$/Euro is worth the investment and cheaper than buying bottled mineral water. An osmosis filter system can last a lifetime and you only need to exchange the filters every once in a while. An osmosis filter is essential if your water has a high EC . Generally an EC above 0.7 mS/cm (or 700 µS/cm) is problematic, especially if you need to fertilize indoor or have a hydroponic system. Mixing your water approx. 50-50 with pure osmosis water solves this problem.
The ideal pH and pH fluctuation in hydroponics depends on several factors that you have to evaluate on an individual basis because each hydroponic system is different due to the following:
In the world of plants each plant species is perfectly adapted to a certain pH range of the soil or water. Hobby gardeners are usually familiar with the different pH requirements of various plants like rhododendron, roses, or conifers, and buy special soil mixes and regulate the pH of water appropriately.
The pH is the measure of the acidity or alkalinity of a solution or substrate. A low pH shows that the solution is acidic and a high pH that it is base/alkaline. The middle value of approx. pH 6.8 is the neutral range. The pH is absolutely vital for all living organisms in various ways.
Nutrient lockout (sometimes referred to as “nutrient lock”) occurs when your cannabis plants can’t absorb nutrients from the soil or the fertilisers you’re using to feed them. One of the primary causes of nutrient lockout is pH imbalance, but it can also be caused by salt buildup near the root zone as a result of feeding with mineral fertilisers (which tend to have a high salt content).
In more scientific terms, pH level has to do with the concentration of hydrogen ions, say in the water you give to your plants. The pH scale is logarithmic to the base 10, which means that water with a pH of 6 is already 10x more acidic than water with a pH of 7.
The Best pH for Growing Cannabis
Using natural fertilisers like compost, worm castings, and bone meal creates a breeding ground for healthy bacteria and fungi that keep the conditions of your soil optimal, so there’s usually no need to monitor the pH of your soil as closely as you would otherwise.
pH measuring kits usually contain a test tube, a bottle of testing solution, and a colour-coded pH chart. Testing the pH of your soil with these kits is super simple:
🧪 Do I Test the pH of My Fertiliser Before or After Adding My Nutrients? Always measure the pH after you add any nutrients or amendments as they will change the pH value of your water. After you mix your nutrient solution, use a pH meter or drops to test its pH level.
pH Up is a strong alkali formula for raising pH. The one from General Hydroponics is made from a base of Potassium Hydroxide and Potassium Carbonate.
pH Down is an acid based formula for lowering pH. General Hydroponics up/down is made from a base of Phosphoric Acid.
As explained above, adjust the pH of your solution a little at a time. Try to use only either Up or Down. If you overshoot with one and then have to readjust with the other you can end up unnecessarily stressing your plants. Mix up a little of the required pH adjuster in a separate jug. Then add them a little at a time to your reservoir. Allow time for the whole reservoir to even out and settle. Better to get it right with 3 slight adjustments than have it wildly swinging up and down.