Agriculture Reference
In-Depth Information
FIGURE 5.8
pH indicator paper.
colorpHast indicator strips as shown in Figure 5.8. These cost about $15 for
100 strips. Paper strips are much easier to handle than liquid dyes that have
to be added to a solution sample and then the resultant color of the liquid
compared with a color pH chart.
Test the pH of the nutrient solution every day and keep records of it, so
you may see any changes taking place. To lower the pH, add acid such as
sulfuric acid (H
2
SO
4
) (battery acid) and to raise the pH, add potassium
hydroxide (KOH), sodium hydroxide (NaOH), or baking soda. You must
wear gloves and protective goggles when using sulfuric acid, potassium
hydroxide, or sodium hydroxide as they burn your skin. These, however,
are most effective in quickly shifting the pH. If you buy them in con-
centrated form, dilute them to about 1 part of acid to 30 parts of water.
Remember: add acid to water!
Your local hydroponic shops also sell more dilute solutions to adjust
the pH that are safer to handle. These are usually termed “pH UP” or
“pH DOWN” solutions (Figure 5.9). These solutions enable the gardener
to maintain optimum pH levels of the nutrient solution. Most are in a liquid
form, but some are available in powder form.
