Tisochrysis lutea

Q:       We ordered algae CCMP463 from your laboratories in 2014. The culture was growing well until recently. Sometimes the algae look one day fine, but they aggregate and settle down overnight. We grow our algae in artificial seawater with F1/2 medium under 14/10 day night conditions. We do airbubble in the culturing flasks (we use 1L or 2L bottles).   Do you have any tip what can prevent aggregation of the algae?

A:       I am afraid that we grow all our cultures in filtered natural seawater with a 13/11 light/dark cycle without aeration.