Hello atulbaliga,
When you say calibrated pH, are you referring to calibrating a
pH meter? Or adjusting the
nutrient solution pH? I asked because I'm not sure what the liquid in the picture is. I assumed you were using a
ph meter because because of the values you were giving, but the picture looks like the color you would get using pH drops at 6.0. So now I'm wondering if the picture is on the calibration fluid used to calibrate a pH meter, or of the pH drops test.
Also have you gotten the water temp down?