We've had a few experiments between us and one that stuck out for me was the effect of having plants above the water line for even a few minutes. Most of us will have some of the plants emersed for a substantial time at water change time which gives the plants the opportunity to 'gulp' in a load of unrestricted CO2 (300-400ppm level as compared to 30ppm below water). So that once the water goes back up and the lights come on they will pearl like mad.
Not knowing your full tank set-up, it is not going to be possible to give all the reasons what/why things are happening for you, but as with John, I get pearling every day. However, when I had Koralia pumps going, this was less evident and I also got more pearling when the CO2 levels were higher prior to adding fish.
So unless your filter is blasting away at the plants I would suspect that it is nothing to do with your filter.
viewtopic.php?f=3&t=4206
This was a good discussion on pearling after water changes (at least I thought so

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