The reason ur last crop turned even more yellow is because when u flush u r releasing the elements in the soil.. u proli didnt flush long enough.
Monitor ur resivior closely, ur PH will drop wen u flush, but u must keep it at 6.5, and ur EC, or PPM/TDS (Im not sure how u read ur nutrient strength) will raise as it pulls salts from the soil. Keep it low, or u are just putting the old salts back in the soil.
Like i said, it takes a few days. Put 2 or 3 times the normal amount of water through the soil as u normally would.
Let me know how u go..
The reason ur last crop turned even more yellow is because when u flush u r releasing the elements in the soil.. u proli didnt flush long enough.