4.5–9 pH Test Strips
Apera Instruments
Hanna Instruments
Bluelab Instruments
Electrical Conductivity & pH Guide
The pH of the hydroponics reservoir should be between 5.5 and 6.5.
Optimum Water pH
TODO
Optimum Water Temperature
Don't add the pH adjusting solution straight to the reservoir or you may shock the plant roots.
Add it to a gallon jug and let dilute for 5 minutes before slowing pouring the solution into your reservoir.
Adjusting pH Levels
Table 1: Optimum range of electrical conductivity (EC) and pH values for hydroponic crops.
| Crops | EC (mS/cm) | pH |
|---|---|---|
| Asparagus | 1.4 to 1.8 | 6.0 to 6.8 |
| African Violet | 1.2 to 1.5 | 6.0 to 7.0 |
| Basil | 1.0 to 1.6 | 5.5 to 6.0 |
| Bean | 2.0 to 4.0 | 6 |
| Banana | 1.8 to 2.2 | 5.5 to 6.5 |
| Broccoli | 2.8 to 3.5 | 6.0 to 6.8 |
| Cabbage | 2.5 to 3.0 | 6.5 to 7.0 |
| Celery | 1.8 to 2.4 | 6.5 |
| Carnation | 2.0 to 3.5 | 6 |
| Courgettes | 1.8 to 2.4 | 6 |
| Cucumber | 1.7 to 2.0 | 5.0 to 5.5 |
| Eggplant | 2.5 to 3.5 | 6 |
| Ficus | 1.6 to 2.4 | 5.5 to 6.0 |
| Leek | 1.4 to 1.8 | 6.5 to 7.0 |
| Lettuce | 1.2 to 1.8 | 6.0 to 7.0 |
| Marrow | 1.8 to 2.4 | 6 |
| Okra | 2.0 to 2.4 | 6.5 |
| Pak Choi | 1.5 to 2.0 | 7 |
| Peppers | 0.8 to 1.8 | 5.5 to 6.0 |
| Parsley | 1.8 to 2.2 | 6.0 to 6.5 |
| Rhubarb | 1.6 to 2.0 | 5.5 to 6.0 |
| Rose | 1.5 to 2.5 | 5.5 to 6.0 |
| Spinach | 1.8 to 2.3 | 6.0 to 7.0 |
| Strawberry | 1.8 to 2.2 | 6 |
| Sage | 1.0 to 1.6 | 5.5 to 6.5 |
| Tomato | 2.0 to 4.0 | 6.0 to 6.5 |
Electrical Conductivity & pH Guide
Table 2: Acceptable values for common nutrients found in water.
| Nutrients | Acceptable value (ppm) |
|---|---|
| Sodium | <50 |
| Calcium | <150 |
| Magnesium bicarbonate | <50 |
| Chloride | <140 |
| Sulfate | <100 |
Electrical Conductivity & pH Guide
If the pH is High
TODO
If the pH is Low
TODO