| Model |
| Non-standardized coefficient | Standardized coefficient | t | Sig. | |
| B | Standard Error | Beta | ||||
| 1 | (constant) | 9.531 | 0.028 |
| 345.676 | 0.000 |
|
| Dissolved oxygen | −0.408 | 0.029 | −0.770 | −14.162 | 0.000 |
|
| Conductivity | 0.829 | 0.258 | 0.216 | 3.215 | 0.002 |
|
| SiO2 | −0.002 | 0.001 | −0.183 | −2.636 | 0.009 |