I agree that silica is a great ph up, and your plants will love it - it improves resistance to fungal and bacterial pathogens, strengthens cell walls, promotes plant growth, increases resistance to insects and pests, as well as heavy metals, improves tolerance to drought and heat stress. But, be aware that too much silica can make the leaves very tough to the point that they may become brittle. I generally use about 1/4 ml per gal at each watering and stop using it a couple of weeks before harvest.
Also, check your ingredients of your silica and be aware of the difference between potassium silicate and monosilicic acid. Many growers think that they’re applying silica products when they’re really applying silicon products, however, not all silicon products are silica. Here is a breakdown to make it easier to understand:
- Silica: aka silicon dioxide (SiO₂). Found in the mineral quartz and a major part of sand.
- Silicic Acid: a general term for compounds that contain silicon (Si), oxygen (O), and hydrogen (H)
- Monosilicic Acid: aka orthosilicic acid Si(OH)₄
- Silicates: compounds containing oxygen and silicon - including potassium silicate and calcium silicate
- Silicon: a chemical element (Si)
Plants can’t take up or use potassium silicate. It must be converted to monosilicic acid by bacteria . Applying potassium silicate does not have the same effects as applying monosilicic acid.
Also, the pH of a solution impacts the form of silicon in solution. Moderately basic (a pH above 8), monosilicic acid will react with minerals which causes the silicon to precipitate out as a solid. So, if you are using silicon to lower the PH of anything above 6.0 you may suffer from precipitation.
Sorry to hijack the thread for a minute, but I felt it was important to discuss the possible dangers of using silicon to lower the ph of any water above 6.0, and to clarify the differences between different “silica” products to avoid confusion.