pH Control

The Importance of pH

PH is the measurement of the acidity or alkalinity of a substance. It is measured from 0 to 14. 0 is the most acidic while 14 is the highest alkaline level. 7 is the neutral pH level. PH level in the soil affects the nutrient solubility for plants. 14 out of the 17 essential nutrients the plant needs comes from the soil. They must be dissolved for them to be soluble for efficient uptake. The best pH level for nutrient uptake is between 5.5 – 6.5 pH so it is important to test the pH level of your soil, growing medium, and fertilizer mix.

How to test your pH level

The easiest and most reliable methods are pH drops and litmus paper. They are best for regular monitoring and maintenance. When there are signs of a problem then it is best to use more accurate testing methods. A high quality pH meter can be used to test the water, fertilizer solution, and growth medium. There are a lot of pH meters available in the market. Choose the one that can provide your needs.

PH adjusting

If there are problem with the pH level of your water, fertilizer mix, or growth medium then you need adjust them yourself.

A pH up or down solution can be used to achieve the desired pH level. PH up solutions generally contain potassium Bicarbonate and/or Sodium Bicarbonate.  Most PH down solutions are Phosphoric Acid and/or Citric Acid. The duration of the effects of the pH solution is dependent on the ingredients used.

Bicarbonates have a long lasting effect on the media solution and fertilizer mix and is best used in hydroponic gardening.

Dolomite is great in stabilizing pH level in soils.

Phosphoric acid are best used in hydroponic gardens and can be keep the pH level longer than citric acid based pH solutions. Although phosphoric acid is not good at acidifying soil grows.

PH is important for soil or hydroponic growing, but much more so for hydroponic.  Because water fluctuates PH over time, temperature, and other environmental responses, PH must be balanced in hydro setups to match that of soil.  PH fluctuation in a hydroponic garden can diminish yield and quality greatly.

pH is the measure of acidity/alkalinity of a solution.  Specifically, pH is a measure of the hydronium ion H3O+. It is based on a logarithmic scale from 0 to 14. “Pure” water has a pH of 7.0. If the pH is less than 7, the solution is acid. If the pH is greater than 7 it is alkaline. Because the scale is logarithmic and not linear, a pH of 6 indicates ten times more H protons than a pH of 7, and a pH of 5 indicates 10 times more protons than a pH of 6.
The ideal pH range for most cannabis crops is between 5.5 and 6.5.
pH is important because it affects availability and absorption of several of the 16 atomic elements needed for plant growth. Maximum absorption of these elements is found at pH readings 5.5 to 6.5. When pH falls below this range many of the macro elements (N, P, K) have less availability, and absorption of the micro nutrients can reach toxic levels.

pH is adjusted by using an acid to lower it or a base to raise it. General Hydroponics’ pH Down and pH Up are designed for this purpose. Many acids and bases are extremely corrosive and dangerous, so care should be used.  Lemon, Lime, and Baking Soda are common household PH adjusters.

How often should I check my pH level?
When first starting out it is a good idea to measure the pH of your water every day, until you get a feel for your system. Measure your water and then add your nutrients. Within an hour check the pH and adjust accordingly. Repeat this process until pH stabilizes. The liquid nutrient Flora Series has special pH buffers to help maintain a desirable pH. It is a good idea to note how much water, nutrients and pH modifiers are needed to obtain the desired values. After several “start- ups” you can generally get a feel for how much acid or base to use for your situation. Frequently pH stays within a desirable range for a considerable time, and then rapidly rises or falls to an extreme. This is usually an indication of the need to do a nutrient change. If you are using hard water, pH has the tendency to climb above 7.5. Sometimes this can be neutralized with acid, though one might consider diluting with filtered water, or adding a reverse osmosis unit in an extreme case.

How much pH Up/Down is needed per gallon?
Start out with one milliliter per gallon. Wait 15 To 30 minutes, and test your water again. Frequently you will only need 1 to 2 ml of pH Up/Down per gallon of water. You may need additional pH Up/Down if you have hard water. Flora Series is pH buffered to facilitate keeping the pH in a favorable range.

The pH in my system drops below 4 every few days after cleaning and refilling. How do I increase the pH and stabilize it?
The easiest way is to continue adding pH Up. This is generally fine because the additional elements that are added are potassium ions. Potassium is frequently the highest element in hydroponic nutrient solutions. Sometimes pH crashes because of the presence of a large amount of microbial activity in the nutrient solution. This is usually a result of poor maintenance of the system due to infrequent nutrient changes or other stresses. The best way to avoid this scenario is to keep a clean system with adequate nutrition.