pearl when adding macros

its more than likely coincidence The pearling starts once the water cannot absorb any more O and therefore it forms in bubbles instead.

Some people get pearling pretty quickly, others never see it

All to do with the rate of growth of the plants alongside the O content of the water.

i.e. no CO2, low light, no surface disturbance may mean no pearling or not until later in the day.

High CO2, high light and water disturbance may mean a couple of hours.

I would put myself in the fast growth with water disturbance region and get pearling after 4-5 hours (which seems a similar time frame to you)

I dose about 2 hours before the lights

AC