What’s your nitrate and phosphate on the fresh salt mix?
I would turn it down a bit, the colour your aiming for is a tea sort of colour, that looks a bit thin.
You might be skimming the bacteria out too quickly.
Pull as much of it of the rock as you can too.
Your po4 is too low too, sounds silly but feed a bit more, for the nopox to work you need both nitrate and phosphate in the water.
How much nopox are you dosing each day?