<4.0 | 4.0 - 4.9 | 5.0 - 5.4 | 5.5 - 5.9 | 6.0 - 7.5 | 7.6 - 8.4 | 8.5 - 9.4 | >9.5 |
Ext. acid | Very acid | acid | Light. acid | Neutral | Light. Alkaline | Alkaline | Very alkaline |