Sunday is a day for water change, so I changed water (tap water) in my tank without my lighting hood, because i had to repair my light (bad contacts). My lights were off, and after water change I saw outgassing bubbles in my aquarium without the lights over it, it look like real pearling from the plants. This was not real pearling, but this may be the reason for better and much more intense pearling after water change, outgassing bubbles in combination with real pearling ?

Turn off your lights, after water change to check your bubbles...