senorinuanswered grow question 4 years ago Credit to Ludacris on rollitup forums:
PH FACTS AND ADJUSTMENTS.
causes of ph fluctuations and pH facts.
When growing in soil any fertilizer you use can cause an excess build up of salts when it decomposes in the soil. This almost always results in a more acidic soil which stunts the plant's growth and causes brown foliage. When using a Hydroponics set-up the nutrient solution can very easily cause a fluctuation in the growing reservoir. Other common reasons as to why soil may become too acidic when doing outdoor grows are rainfall, leaching, organic matter decay and a previous harvest of a high yeild crop in the same soil. In dry climates, such as the desert Southwest US, Spain, Australia, etc., irrigation water is often alkaline with a pH above 7. The water in rainy climates, such as the Pacific Northwest of North America, the UK, Netherlands and Northern Europe, is often acidic with a pH below 6. Lightly sandy soils with little clay and organic matter are quicker too become more acidic. Another common mistake is that a grower will mix his soil unevenly, leading to "hot spots" in the growing medium, so mix all ratios as well as you can.
How do I raise/lower my pH?
A great way to regulate the pH of your soil is to use Dolomite Lime(calcium-magnesium carbonate). While growing Cannabis plants in containers, mix one cup of fine dolomite lime for each cubic foot of soil, then lightly water it. After watering, mix it once more and wait a day or two before checking the pH. While growing in an outdoor garden, follow the dolomite lime manufacturers instructions. Dolomite Lime works well because it has a neutral pH rating of 7.0 and tends to keep the soil a constant pH throughout the entire life cycle of the plant. This is a highly recommended method of regulating your soil pH.
If you find the pH of your soil or Hydroponic reservoir to be too acidic or basic you could add either pH up or pH down. These are chemicals sold at places like Home Depot or any Gardening store. They usually come in one liter bottles and are to be diluted in the water used to water the soil growing plants or the Hydroponic reservoir according to directions on the packaging.
Some examples of Home remedies to raise/lower pH are as follows:
1.Lemon juice. 1/4 tbsp can bring a gallon of tap-water from 7.4 to 6.3.
2.Phosphoric acid. lowers pH and provides Phosphor too!
3.Nitric acid. lowers pH.
4.Hydrochloric acid. strongest way to lower pH
5.Hydrated lime. flush soil with a teaspoon per gallon of water to raise pH.
6.Baking Soda. eats acids to raise pH.
7.Calcium carbonate. raises pH (very strong)
8.Potassium silicate. raises pH.